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NATIONAL   GEOGRAPHIC  SOCIETY 

GARDINER    O.  III-BBARD,  PRESIDENT 


THE  PHYSIOGRAPHY 


OP  Tine 


UNITED  STATES 


TEN   MONOGRAPHS   IsV   .T.   W.   POWKl.L,   X.  S.  KIIALEIi,  I.  C.  RVSSELL,  nAILF.Y   WILLIS, 
('.  WILLAIU>    HAYES,  J.  S.  DILLKR,   \V.  M.   UAVIS,  O.  K.  (ilLBERT. 


NEW  YORK    •  :  •    CINCINNATI    •  :  •    CHICAGO 

AMERICAN    BOOK    COMPANY 

1897 


Copyrit^ht,  1 S9G,  by 
American  Book  Company. 


^03 

Hz\ 

PEEFACE. 

The  study  of  the  origin  of  eartli  forms  lias  made  remark- 
able progi'ess  dui-ing  the  last  twenty  years,  so  that  it  is 
scarcely  exaggeration  to  say  that  a  new  science  has  been 
created.  While  those  who  have  aided  in  its  development 
are  learned  investigators  exploring  the  frontiers  of  human 
knowledge,  the  more  impoi'tant  results  are  so  simple 
as  to  be  appreciated  not  only  by  intelligent  lajnnen, 
but  even  by  school  children.  Practical  experiment  has 
shown  that  the  explanation  of  the  work  of  rain  and 
streams  in  the  shaping  of  the  eartli  is  one  of  the  most 
attractive  and  fi-uitful  nature  studies  which  can  be  intro- 
duced into  pi'imary  and  secondary  schools,  and  a  move- 
ment has  been  organized  among  educators  for  its  extensive 
introduction.  Professor  W.  M.  Da\ds  of  Harvard  Uni- 
versity, who  is  a  leader  in  this  movement,  proposed 
about  two  years  ago  that  the  National  Greographic  Society 
undertake  the  preparation  of  a  series  of  essays  on  geo- 
graphic sul)jects,  enlisting  in  the  work  some  of  the 
numerous  specialists  in  its  membership,  and  making  such 
arrangements  for  puljlicatiou  that  the  essays  should  be 
accessible  to  the  teachers  of  the  land.  This  ])roposition 
was  developed  and  discussed  at  a  conference  held  in 
Washington  in  June,  1894,  and  a  few  months  later  the 
managers  of  the  society  took  action,  appointing  an  editing 
committee  under  the  chairmanship  of  Major  J.  W.  Powell. 
AiTangements  for  publication  were  made  with  the  Amer- 
ican Book  Company,  and  this  volume  is  the  first  product 
of  that  cooperation. 


CONTENTS, 


PAGE 

Physiographic  Processes 1 

By  J.  W.  PoweU. 
Physiographic  Features 33 

By  J.  W.  Powell. 
Physiographic  Regions  of  the  United  States 65 

By  J.  W.  Powell. 
Present  and  Extinct  Lakes  op  Nevada 101 

By  I.  C.  Russell. 
Beaches  and  Tidal  Marshes  ok  the  Atlantic  Coast    .    .    .    .137 

By  N.  S.  Sbaler. 
The  Northern  ^^palachians 169 

By  Bailey  Willis. 
Niagara  Falls  and  their  History 203 

By  U.  K.  Gilbert. 
Mount  Shasta,  a  Typical  Volcano 237 

By  J.  S.  Diller.  " 

The  Physical  Geography  of  Southern  New  England  ....  269 

By  W.  M.  Duvis. 

The  Southern  Appalachians 305 

By  C.  Willard  Hayes. 


PHYSIOGRAPHIC    PROCESSES. 


By  J.  W.  Powt:ll. 


Physiography  is  a  description  of  the  surface  features  of  the 
earth,  as  bodies  of  air,  water,  and  laud.  lu  it  is  usually  included 
an  explanation  of  theu*  origin,  for  such  featui'es  are  not  properly 
understood  without  an  explanation  of  the  processes  by  which 
they  are  formed. 

The  earth  has  three  moving  envelopes.  These  are,  first,  the 
atm.osj)here,  which  covers  it  to  a  great  depth ;  second,  the  water, 
which  covers  more  than  three  fourths  of  its  surface  with  sea, 
lake,  stream,  and  ice  field,  while  the  whole  is  covered  intermit- 
tently with  clouds ;  and,  third,  a  garment  of  rock  in  beds,  layers, 
and  piles. 

These  outer,  middle,  and  inner  garments  of  air,  water,  and 
rock  are  forever  in  motion.  Each  envelope  has  a  system  of  mo- 
tions of  its  own,  j'et  all  three  act  and  react  upon  one  another  in 
such  a  manner,  that,  wliile  their  motions  are  independent  in  part, 
they  are  at  the  same  time  interdependent  in  part. 

Within  the  envelopes  is  the  great  central  body  of  the  earth, 
which  is  but  little  known,  but  about  which  there  has  been  mudi 
speculation.  Many  scientific  men  believe  it  to  be  solid,  and  deem 
that  this  is  proved  from  certain  evidence  dei-ived  from  the  tides ; 
other  scientific  men  believe  that  the  interior  of  the  earth  is  in  a 
sublluid  condition,  due  to  the  pressure  of  the  superincumbent 
envelope  of  rock.  For  present  pui'poses  it  is  unnecessary  to 
weigh  the  evidence  for  these  two  hypotheses  and  judge  between 
them.  Wliat  we  need  is  to  imderstand  clearly  that  there  are 
three  pretty  well  defined  envelope's  tliat  are  in  motion,  and  ever 
interacting  among  themselves  in  sucli  a  manner,  that  there  are 
sea  bottoms,  plains,  plateaus,  mountains,  hills,  and  valleys  in  the 
rock  envelope ;  there  are  seas,  lakes,  sti-eams,  and  clouds  in  the 
aqueous  envelope ;  and  there  are  winds  in  the  atmospheric  en- 
velope ;  and  that  the  winds,  clouds,  storms,  streams,  lakes,  seas, 

(Copyright,  1895,  by  American  Book  Company.) 


2  PHYSIOGRAPHIC  PROCESSES. 

^silleys,  hills,  mountaius,  plateaus,  plaius,  aud  sea  floors  are  all 

related  to  one  another,  aud  ahvays  chaugiiig.    That  which  is  sea 

floor  at  oue  time  is  plaiu  at  another,  phiteau  at  still  another, 

mouutaiu  summit  at  stiU  another ;  and  hills  aud  valleys  follow 

in  succession,  for  the  land  seems  to  be  always  rising  and  faUiug. 

Another  gi-eat  fact  requires  mention  in  this  place.     It  is 

generally  beheved  that  the  earth  is  surrounded  by  and  pei-- 

meated  with  an  ether  which  extends  in  space  through  the  solar 

system  and  into  the  region  of  fixed  stars.     By  means  of  this 

ether  the  earth  is  m  constant  communication  with  the  moon, 

X  the  sun,  every  planet,  and  every  distant  orb,  and  through  it 

.  comes  to  the  earth  a  constant  flow  of  light  and  heat  from  the 

1  fiery  globes  of  space. 

THE   ATMOSPHERIC   ENVELOPE. 

Changes  in  the  air  come  chiefly  in  four  ways: — 

First,  It  moves  with  the  rest  of  the  earth,  of  which  it  forms 
a  part,  in  rotation  about  the  central  axis. 

Second,  Being  heated  at  the  tropics  and  cooled  in  the  polar 
regions,  the  air  about  the  equator  rises,  and  flows  poleward  in 
both  dii-ections.  In  the  polar  regions  the  air,  being  cooled,  sinks, 
and  flows  toward  the  ecpiator.  The  gi'eat  velocity  of  the  winds 
in  equatorial  regions  as  they  are  carried  eastward  with  the  rotat- 
ing earth,  and  the  small  velocity  of  the  polar  -n-inds  due  to  the 
same  cause,  interact  with  the  polar-equatorial  currents,  so  that 
the  air  flowing  toward  the  jwles  is  turned  eastward,  while  the 
air  flowing  toward  the  equator  is  turned  westward. 

Third,  The  vapor  of  water  from  the  surface  of  the  sea  and 
land  is  carried  in  the  clouds  by  the  winds,  aud  from  time  to  time  is 
discharged  from  the  air  as  rain.  In  this  discharge  gi-eat  changes 
of  temperature  are  involved,  and  vertical  currents  of  air  are 
thus  set  up  which  greatly  modify  the  direction  and  velocity  of 
the  ^vinds. 

Fourth,  The  surface  of  the  land  affects  the  dii-ection  of  the 
lower  winds:  for  mountains  change  the  direction  of  air  cui-reuts; 
hills  turn  the  winds  through  valleys ;  and  cliffs,  banks,  ledges, 
and  rocks  produce  eddies  in  the  lower  atmosphere. 

The  effect  of  these  four  processes  is  to  make  the  winds  seem 
fickle,  and  yet  they  are  ever  obeying  law. 

Above  the  surface  of  the  earth  the  winds  become  more  con- 


THE  AQUEOUS  ENVELOPE.  3 

staut  as  they  are  more  and  more  governed  by  the  gi'eat  laws 
which  change  with  the  hours  of  the  day  and  the  seasons  of  the 
year. 

Climatic  temperature  is  the  temperature  of  the  air,  measured 
in  the  shade  so  as  to  avoid  the  direct  radiation  of  th<>  sun.  This 
temperature  decreases  from  the  equator  to  the  poles.  Thus  there 
is  a  latitudinal  change  of  temperature.  Other  things  being 
equal,  the  higher  the  latitude  the  cooler  the  air. 

The  earth  revolves  on  its  axis,  which  gives  us  day  and  night. 
The  air  is  warmer  by  ilay  and  cooler  l)y  night. 

Then  the  axis  of  the  earth,  about  which  it  revolves  in  its 
daily  rotation,  is  inclined  to  the  plane  of  the  orbit  of  the  earth 
in  its  revolution  about  the  sun ;  for  this  reason  the  poles  are 
turned  alternately  toward  the  sun,  and  tliis  produces  a  summer 
and  winter  every  year. 

Temperatvu'e  has  still  another  variable,  which  is  of  great  im- 
portance in  the  study  of  climate :  tliis  is  altitude,  or  tlic  elevation 
of  the  land  above  the  level  of  the  sea.  In  ascending  througli  the 
air  in  a  baUoon,  it  is  found  to  be  cooler  as  the  aerial  voyager 
rises ;  so  in  ascending  from  plains  to  plateaus  the  upper  regions 
are  found  to  be  cooler,  and  in  climbing  from  valley  to  hill  and 
from  hill  to  mountain  a  like  change  of  temperature  is  oliserved. 
The  summits  of  many  high  mountains  of  the  world  are  in  regions 
of  perpetual  snow  and  ice. 

Thus  there  is  latitudinal,  diurnal,  seasonal,  and  altitudiual 
variability  of  temperature,  and  to  all  of  these  must  be  added  the 
variability  which  arises  with  changing  winds  and  conditions  of 
moisture. 

The  diurnal  and  annual  motions  of  the  earth,  and  then-  rela- 
tions to  the  movements  in  the  air  and  ocean,  is  a  subject  so  well 
taught  in  our  schools  that  it  need  not  be  carefully  treated  here ; 
but  reference  is  mjide  to  it  for  the  purpose  of  sliowing  the  way 
in  which  it  enters  into  the  subject  of  physiography. 

THE   AQUEOUS   ENVELOPE. 

The  envelope  of  water  is  changeable  in  a  variety  of  ways:  — 

First,  As  the  moon  revolves  about  the  (^arth  from  east  to  west, 

gravity  drives  the  water  behind  it,  so  that  the  tides  roll  their 

waves  against  the  eastern  shores ;  but  as  the  moon  proceeds,  the 

tides  roll  back  eastward  to  beat  in  waves  against  the  westei'u 


4  PHYSIOGKArHIC  PROCESSES. 

shores.  So  with  the  revolving  moon  the  tides  sweep  back  and 
forth  across  the  surface  of  the  sea,  and  alternately  lash  the  shores 
with  their  crested  waves. 

Second,  Tlie  seas  are  heated  mider  the  tropics,  and  cooled  in 
polar  zones;  so  that  the  water  of  the  equatorial  regions,  wanned 
and  ox]»anded,  flows  over  the  surface  northward  and  southward 
toward  the  pt)les,  and  the  waters  cooled  in  the  polar  regions  sink, 
and  flow  toward  the  equator. 

The  varying  rotational  velocity  of  the  earth's  suiface  at  differ- 
ent latitudes  —  from  the  equator,  wliere  it  is  more  than  one  thou- 
sand miles  an  hour,  to  the  poles,  where  it  is  i)ractically  nothing  — 
interacts  on  flowing  waters,  as  on  the  winds,  and  makes  those 
which  flow  towai'd  the  poles  turn  to  the  eastward  against  the 
westward-facing  shores.  Bo  all  surface  currents  drift  eastward  in 
going  toward  the  poles.  The  currents  thus  formed  are  deflected 
by  continental  shores  and  oljstriicting  islands,  so  that  currents 
more  or  less  clearly  defined  are  established  in  the  sea,  modified 
to  some  slight  extent  by  the  great  gulfs  and  the  outpouring  rivers 
from  the  land  Avhere  the  currents  follow  the  shore. 

ThinJ,  The  winds  drifting  over  tlie  sea  beat  its  surface  into 
waves.  When  the  winds  are  lulled,  the  billows  go  to  rest,  and 
the  sea  is  calm  and  glassy;  Init  when  the  storms  rise,  the  billows 
rage. 

Fourth,  The  heat  of  the  sun  and  other  bodies  of  space,  aided 
by  drying  winds,  evaporates  the  waters  'from  the  sea;  and  the 
vapor  thus  formed  is  drifted  by  the  winds  and  gathered  into 
clouds,  and  precipitated  upon  the  earth,  where  it  gathers  again 
into  rills,  Itrooks,  creeks,  and  rivers,  to  roll  back  into  the  sea. 

Fifth,  In  high  southern  and  northern  latitudes,  and  at  gi'eat 
altitudes  in  the  temperate  and  torrid  zones,  the  moisture  in  the 
atmosi)here  is  congealed,  and  falls  to  the  earth  as  snow,  and  thus 
mantles  the  earth  with  a  robe  of  ice.  In  high  altitudes  and  lati- 
tudes the  snow  accumulates  in  excess  of  the  evaporation  mitil 
great  ice  fields  are  formed.  Under  pressure,  ice  flows  in  some 
I'espects  like  water,  but  very  slowly.  On  tlu^  sunnnit  of  the 
mountains  of  tropical  ami  temperate  regions  such  ice  fields  are 
formed,  filling  the  goi'ges,  and  extending  over  the  crags  and  peaks. 
in  high  latitudes  at  the  north  and  at  the  south,  gi'eat  ice  fields 
accumulate  on  the  plains  and  plateaus,  as  well  as  on  the  moun- 
tains, and  glaciers  of  vast  extent  are  thus  formed.  The  ice-cov- 
ered area  about  the  poles  is  variable.     In  some  regions  and  at 


RAINFALL,  O 

.some  times  it  extends  farther  toward  the  temperate  zone,  while 
in  otlier  regions  and  at  other  times  the  ice  field  retreats. 

Waters  have  constant  mentions  and  variable  motions.  The 
tides  are  somewhat  constant,  and  yet  somewhat  varialjle ;  the 
waves  have  elements  of  constancy  and  elements  of  variability ; 
the  clouds,  in  so  far  as  they  depend  on  evapoi-ation,  have  ele- 
ments of  constancy  and  elements  of  varialnlity,  derived  from  the 
exposure  of  surfaces  to  the  sun  and  constant  and  variable  winds. 
After  the  water  has  been  evaporated  in  the  heavens,  it  drifts  with 
the  winds,  which  are  in  part  constant  and  in  part  vai-iable.  The 
waters,  like  the  winds,  are  modified  l»y  the  rocky  envelope;  for, 
though  largely  under  the  sea,  it  is  in  many  regions  but  little 
below  the  surface  of  the  sea,  and  influeuees  its  currents  and  the 
evaporation  of  its  waters.  Other  portions  of  the  rock  envelope 
lie  above  the  sea-level,  as  plains,  plateaus,  mountains,  and  hills, 
and  by  their  geogi-aphical  distribution  break  the  course  of  the 
winds,  and  greatly  influence  both  evaporation  and  precipitation. 
Lands  gather  the  waters  wliieli  fall  from  the  clouds  into  streams, 
which  are  governed  by  the  land  slopes  until  they  empty  into  the 
sea.  So  the  winds  influence  the  waters,  and  the  waters  influ- 
ence the  winds,  and  the  rocks  influence  the  waters  and  the  winds, 
and  the  winds  and  waters  influence  the  rocks.  All  —  rock,  water, 
and  air  —  are  ever  in  motion,  governed  in  part  by  constants  and 
in  part  by  variables. 

Rainfall. —  The  evaporation  of  water  from  the  surface  of  the 
earth  is  very  irregular.  In  general  there  is  more  evaporation 
from  water  surfaces  than  from  land  surfaces,  more  in  dry  weather 
than  in  wet  weather,  more  in  hot  weather  than  in  cold  weathei", 
and  more  in  high  winds  than  in  calms.  As  the  water  is  evap- 
orated from  the  sea  and  the  land,  it  is  carried  away  in  the  air 
to  form  clouds,  which  arc  in  part  gathered  Ity  diverse  winds, 
and  in  jjart  directed  by  diverse  lands  into  diverse  regions.  It  is 
in  this  manner  that  the  water  is  precipitated  from  the  clouds  irreg- 
ularly over  the  surface  of  the  earth,  some  regions  receiving  more, 
other  regions  less,  while  in  every  region  the  rain  is  intermittent. 
A  great  rainstorm  may  come  at  one  time,  and  a  great  drought  at 
another:  now  the  lands  are  flooded,  and  then  the  lands  are  parched. 
There  are  regions  of  the  earth  where  the  ainiual  rainfall  is  more 
than  six  hundred  inches,  an<l  there  are  other  regions  where  the 
;  annual  I'ainfall  is  not  more  than  three  inches.  Thus  in  passing 
from  land  to  land  great  irregularity  of  rainfall  is  discovered.    But 


6  PHYSIOGEAPHIC  PROCESSES. 

within  the  same  laud  there  is  vaiiability  from  time  to  time.  Max- 
iimiui  storms  may  jjive  more  than  twenty  inches  of  rain,  wliile 
that  given  by  niinimmu  storms  cannot  even  be  measnred  iu 
inches,  the  iniit  is  too  large ;  a  mere  dampening  of  the  smface 
results  therefrom. 

Run-off.  —  The  land  is  everywhere  traversed  by  a  netwoi'k  of 
streams — as  rivers,  creeks,  and  brooks — which  meander  from 
tlie  highlands  down  the  vallej^s,  little  and  great,  uniting  again 
and  again,  until  as  rivers  they  roll  into  the  sea. 

In  lands  of  great  rainfall  the  streams  are  many  and  large, 
whereas  in  lauds  of  small  raiufall  the  streams  are  fewer  and 
smaller ;  but  the  decrease  iu  the  number  and  size  of  the  streams 
is  much  greater  than  the  decrease  iu  precipitation.  Stream 
aridity  is  greater  than  atmospheric  aridity,  iu  arid  climates, 
where  the  rate  of  precipitation  is  less,  the  rate  of  evaporation  is 
gi'eater;  so  that  aridity  promotes  evaporation,  and  thus  still 
more  diminishes  the  size  and  number  of  the  streams.  Under 
average  conditions,  where  the  mean  annual  rainfall  is  forty 
inches,  about  twenty  inches  of  the  precipitation  is  evapoi-ated 
from  the  surface  of  the  land,  and  twenty  inches  is  gathered  into 
streams  to  be  car)-ied  away  to  lakes  and  seas.  If  the  mean  rain- 
fall is  more  than  this,  the  mean  run-off  by  streams  is  more  tlinii 
half  theruu-off;  but  if  the  mean  raiufall  is  less,  the  mean  run- 
off is  less  than  hah'  the  rainfall.  AVhere  the  raiufall  is  but  ten 
inches  anuuallj',  permanent  streams  are  not  formed.  "S\nien 
they  are  found  in  such  regions,  they  have  their  sources  iu 
other  regions  where  the  rainfall  is  greater.  Other  conditions 
being  equal,  the  raiufall  is  greater  about  mountains,  as  moini- 
tains  furnish  conditions  for  increased  precipitation.  There  are 
regions  in  the  United  States,  as  elsewhere  in  the  world,  where 
the  raiufall  is  less  than  twenty  inches,  and  where  streams 
of  water  are  gathered  by  mountains  to  roll  down  in  deep 
rocky  gorges.  Such  streams  usually  diminish  in  size  as  they 
procetnl,  uutil  their  waters  are  evaporated.  Often  they  end  in 
luarshes  and  swampy  lakes,  where  th(>  sands  are  deposited  by 
the  djnug  rivei's  iuul  creeks.  Locally  these  are  often  called 
6'w/r.s',-  and  many  i)eople  who  do  not  understand  the  laws  of 
evaporation,  precipitation,  and  run-off,  suppose  that  the  streams 
actually  sink  beneath  the  surface  of  the  earth,  to  flow  in  under- 
ground channels.  There  is  a  popular  belief  that  there  are  many 
underground  rivers  of  this  character  in  the  dry  regions  of  the 


FLOODS.  7 

far  West.  In  all  regions  thei*e  are  uudergi-ound  waters,  as  the 
loose  soils,  sands,  and  gravels  retain  much  water ;  and  the  sands 
at  the  mouth  of  a  vanishing  stream  also  contain  more  or  less 
subterranean  water  of  this  character,  which  is  more  slowly  evap- 
orated into  the  heavens ;  but  these  so-called  lost  rivers,  carrjdng 
waters  from  moiintain  streams  of  arid  regions,  do  not  exist,  and 
the  popular  error  in  this  respect  has  no  foundation  in  fact.  Yet 
there  are  lost  rivers  of  another  character,  where  streams  disai)pear 
from  the  surface  and  run  iu  undergi'ound  channels,  to  reappear 
below. 

On  the  plains  and  in  the  valleys  of  regions  where  the  annual 
rainfall  is  less  than  ten  inches,  or  even  less  than  three  inches, 
intermittent  streams  ai'e  sometimes  formed.  This  little  rain 
often  comes  in  great  storms,  anil  storm-water  streams  are  thus 
produced,  whose  waters  flow  for  a  time  as  ci'eeks  of  mud,  but  are 
soon  lost  by  evaporation.  The  mud  which  is  thus  swept  down 
from  the  hills  and  higher  ridges  is  deposited  in  the  valleys  Ix^low ; 
and  gradually,  through  years  and  centuries,  the  valleys  and  low- 
lands are  covered  to  great  depths  by  such  deposits. 

In  regions  of  country  where  the  rainfall  is  twenty  inches  or 
more,  permanent  streams  may  be  formed  which  ultimately  dis- 
charge into  the  sea;  and  the  sands  which  are  washed  down  by 
flood  waters  are  deposited  in  part  along  the  course  of  such  streams, 
to  be  carried  along  again  when  other  rains  come,  until  finally  they 
are  swept  out  to  the  ocean,  whei-e  they  are  deposited  as  deltas  or 
carried  along  the  seashore,  to  be  built  up  in  banks  against  the 
land  or  to  be  formed  into  fringing  islands. 

Floods. —  Stream  channels  are  tlie  aqueducts  by  which  th<^ 
water  not  evaporated  runs  off.  The  streams  cut  their  own  chan- 
nels. Where  there  is  more  water  to  be  carried,  the  channel  is 
made  deeper  or  wider  (one  or  ])oth),  and  for  this  pvu'pose  there  is 
more  water  to  do  the  work.  But  the  channels  will  not  hold  all 
the  water  of  great  rainstorms :  hence  floods  come,  for  a  flood  is 
the  flow  of  a  stream  over  the  banks  of  its  channel.  If  a  stream 
cuts  its  own  channel,  and  if  the  greatei-  the  amount  of  water  the 
greater  the  size  of  the  channel,  other  things  being  equal,  why  is 
it  that  floods  come  f  This  question  must  be  answered  by  ex- 
plaining the  manner  in  which  stream  channels  are  choked. 
There  are  many  minor  ways  by  which  they  are  obstructed,  but 
most  of  these  may  be  neglected,  as  they  are  of  small  importance; 
l)ut  the  two  principal  methods  require  attention. 


8  PHYSIOGRAPHIC  PEOCESSES. 

By  the  first  method,  a  small  stream  chokes  a  lai'ger  one ;  and 
by  the  second  method,  a  stream  chokes  itself.  Let  us  understand 
the  first  one. 

Consider  a  stream  without  tributaries.  Suppose  that  all  the 
water  carried  by  it  is  derived  from  one  source,  some  mammoth 
spring  with  a  constant  fsupply,  and  that  no  water  is  added  to  its 
volume  on  its  way  to  the  sea.  Under  such  circumstances,  the 
stream  cuts  its  own  channel  from  source  to  outlet  large  enough 
to  carry  the  volume  of  water,  and  it  never  overflows  its  bank. 
Now  suppose  another  stream  is  tm-ned  into  it,  and  that  this  trib- 
utary drains  a  region  of  country  where  thei'e  are  intermittent 
rains.  When  the  rains  come,  the  new  stream  has  a  large  volume 
of  water  loaded  with  mud  washed  from  the  hills  and  valleys, 
where  the  rains  are  caught  which  supply  its  volume.  When  the 
muddy  stream  enters  the  river,  the  sands  and  gi-avels  are  in  jtart 
deposited  below  the  junction.  This  forms  a  dam  or  obstruction, 
and  tends  to  cause  a  flood  in  the  main  stream  above  the  junction. 
Let  other  streams  be  turned  into  the  main  river ;  and  wherever 
such  a  lateral  stream  comes  in,  a  dam  is  constructed  beloAv  the 
junction.  Now,  the  river  has  a  series  of  dams  constructed  along 
its  course,  each  one  of  which  tends  to  cause  the  river  to  overflow 
its  banks.  The  dams  constructed  in  this  manner  are  washed  out 
and  built  again,  and  washed  out  and  Ijuilt  again,  from  time  to 
time.  Sometimes  a  series  of  these  dams  has  been  constructed 
just  before  some  great  rainfall,  so  that  the  stream  is  in  no  condi- 
tion to  carry  the  greater  supply;  and  a  flood  results.  It  is  in  this 
manner  that  large  streams  are  choked  by  smaller  ones,  and  that 
floods  arise  therefrom. 

Now,  it  must  be  understood  how  streams  choke  themselves. 
'^\nieu  the  waters  are  low  in  any  stream,  they  are  clear.  When 
the  waters  are  high,  they  are  muddy,  for  the  rains  which  cause 
the  increase  of  voluiue  wash  the  surface  soil  into  the  streams. 
Rain  thus  makes  the  river  muddy.  The  mud  lirought  into  the 
stream,  being  heavier  than  the  water,  sinks  to  the  bottom.  Where 
the  waters  are  SAvift,  but  little  nuul  falls ;  where  the  waters  are 
quiet,  much  mud  falls.  The  waters  are  swifter  around  the  outside 
of  a  bend,  and  slower  on  the  inside  of  it.  From  this  slower  water 
the  mud  is  deposited,  so  the  bank  of  the  inner  curve  grows.  As 
the  bank  grows,  the  water  is  piished  over  against  the  other  bank 
on  the  outer  side  of  the  curve,  where  its  flow  is  increased  in 
velocity  so  as  to  cut  the  bank,  and  load  more  material  upon  the 


'I 


THE  ROCK   ENVELOPE.  9 

stream.  The  new  load  is  in  part  thrown  down  again  at  the  next 
bend  on  the  opposite  side,  where  the  water  is  comparatively  still. 
The  first  curve  increases  itself  Ijy  building  up  on  the  inside,  and 
cutting  down  on  the  outside.  In  the  same  manner  the  second 
curve  is  increased  in  the  opposite  direction  by  building  up  on  one 
side,  and  cutting  down  on  the  other.  So  it  is  that  rivers  not  only 
cut  their  own  channels,  but  change  then-  own  courses  from  time 
to  time.  In  this  change  the  stream  is  constantly  depositing  new 
obstructions,  forming  dams,  which  are  known  as  bars;  so  that, 
when  some  great  rainstorm  comes  after  such  obstractious  Ikia'c 
been  built,  the  water  cannot  be  carried  away  by  the  channel,  and 
it  overflows  its  banks,  and  there  is  a  gi'eat  flood. 

So  one  stream  obstructs  anothei-,  and  a  stream  obstructs  itself. 
All  floods  are  ultimately  caused  by  obstruction,  and  obstructions 
are  chiefly  caused  by  one  or  both  of  the  methods  described. 

Thus  far  we  have  considered  the  regimen  of  streams  in  a  state 
of  nature.  Wlien  man  comes  with  tlie  arts  of  civilization  to 
change  the  surface  of  the  earth,  additional  disturbing  factors 
enter  into  the  problem.  Man  i)lows  the  fields,  and  the  side 
streams  carry  additional  amounts  of  detritus,  and  the  obsti'uctiiig 
dams  are  multiplied  and  enlarged ;  he  changes  the  courses  of  the 
smaller  streams,  and  thus  introduces  disturbing  elements  into  the 
larger.  For  the  purpose  of  obtaining  water  powers,  he  builds 
dams,  and  again  changes  and  introduces  new  elements  into  the 
regimen.  Many  of  the  things  tliat  man  does  upon  the  surface  of 
the  earth  have  an  influence  upon  the  ruu-ofl!,  and  generally  in- 
crease the  violence  of  floods;  l)ut  in  lands  where  ii'i'igation  is 
practiced  the  waters  are  taken  away  from  their  natural  channels 
and  spread  over  the  soils,  to  be  reevaporated  into  the  heavens ; 
and  thus  the  streams  are  made  smaller,  and  the  floods  are  dimin- 
ished or  entirely  prevented. 

THE  KOCK  ENVELOPE. 

The  crust  of  the  earth  is  changeable  in  a  variety  of  ways :  — 
First,  It  rises  and  sinks  very  slowly,  so  that  usually  the 
changes  cannot  be  perceived,  except  by  comparing  some  level  of 
land  with  the  level  of  the  sea  at  long  intervals  of  time ;  as  tlie 
hour  hand  of  the  clock  is  not  seen  to  move,  but  known  to  move 
only  by  intervals  of  change  from  houi-  to  hour.  But  there  may 
be  a  time  when  this  change  is  at  once  apparent ;  that  is,  wlien  a 


10  PHYSIOGRAPHIC  PKOCESSES. 

fissure  is  formed  in  the  stouy  crust,  on  one  side  of  whicli  the 
laud  drops,  or  ou  the  other  is  uplifted,  or  perhaps  the  one  is 
dowuthro\vu  aud  the  other  uplifted  at  the  same  time.  The 
tremor  formed  from  such  a  movement  may  be  felt  as  an  earth- 
quake over  thousands  of  square  mUes. 

Second,  When  such  rents  are  formed  in  the  crust  of  the  earth, 
molten  matter  is  often  ejected  which  poxu-s  out  in  great  streams. 
In  this  manner  floods  of  lava  are  spi-ead  over  the  sm-face,  which, 
on  cooling,  become  great  beds  of  rock. 

Third,  ^Mjeu  the  rains  come,  and  the  storms  beat  upon  the 
mountains  and  hills,  their  sands  are  washed  into  the  streams, 
and  by  them  are  carried  awaj\  The  materials  brought  down  by 
the  streams  from  valleys,  hills,  plains,  plateaus,  and  mountains, 
are  discharged  as  sands  aud  clays  into  the  lakes  and  seas,  where 
they  sink.  In  this  manner,  by  rains  and  rivers,  the  lands  are 
carried  away,  and  new  lands  are  formed  along  the  shores  of  lakes 
aud  seas. 

Seas  have  their  tides  and  waves,  and  the  lakes  their  waves, 
which  beat  against  the  shores,  and  undermine  the  banks  and 
cliffs,  and  spread  bowlders,  gravels,  sands,  and  clays  along  the 
margin  of  the  waters ;  and  all  these  materials  are  gradually  car- 
ried out  by  the  undertow  to  a  distance  from  the  land.  At  the 
same  time  the  materials  brought  down  with  the  streams  are  car- 
ried by  currents,  and,  as  they  sink,  they  are  commingled  with  the 
detritus  formed  by  waves.  In  this  manner  lakes  are  slowly  filled, 
and  the  seas  are  ever  accumulating  new  materials  upon  their 
shores  and  on  their  bottoms. 

So  there  are  three  methods  by  which  the  rocks  change  their 
positions.  The  first  is  by  displacement,  when  some  portion  of  the 
crust  is  upheaved  or  dropped  d(iwn;  the  second  is  by  volcanic 
action,  when  rocks  are  poured  from  the  interior  of  the  earth  as 
lava,  or  hurled  out  by  explosions  as  cinders  and  dust ;  and  the 
third  is  by  transportation,  when  rock  materials  are  carried  from 
one  place  to  another  by  streams,  waves,  and  winds. 

The  three  methods  of  change  in  the  stony  crust  have  interest- 
ing relations  to  one  another.  As  the  land  is  upheaved,  it  is  more 
exposed  to  rains  and  rivers ;  and  the  highm-  it  is  carried,  the  more 
rapidly  is  it  worn  doAvn  or  degraded  by  these  aqueous  agencies. 
By  this  process  of  degi-adation  the  cnist  or  rock  envelope  is  weak- 
ened more  and  more,  and  still  rises  to  be  attacked  l)y  the  waters. 
Tims  more  fissures  are  formed,  more  earthquakes  occur,  aud 


KINDS   OF  ROCK.  11 

through  the  fissures  come  more  and  more  bodies  of  lava,  cinders, 
and  ashes.  The  process  of  degradation  by  water  seems  thus  to 
I  faciUtate  the  process  of  upheaval  and  the  process  of  eruption.  But 
a  time  comes  when  such  upheaval  and  degradation  are  checked, 
for  reasons  not  fully  known  to  the  geologist ;  and  slowly  through 
the  years,  and  still  more  slowly  through  the  centm-ies,  and  very 
slowly  through  centuries  of  centuries,  the  upheaval  is  brought  to 
an  end,  and  the  mountains  and  hills  are  then  ever  more  slowly 
degraded  until  they  are  brought  to  the  level  of  the  sea. 

As  the  land  is  upheaved,  the  sea  margin  receiving  the  detritus 
is  thus  loaded,  and  this  load  jjresses  it  down  more  and  more, 
until  at  last  the  process  of  siuking  ceases  slowly  with  the  glower 
upheaval  of  the  land. 

Why  this  process  of  sinking  ceases,  like  the  process  of  up- 
heaval, is  not  clearly  known ;  but  the  fact  that  such  changes  do 
cease  is  well  known. 

It  was  shown  above  how  rising  areas  of  laud  Ijecome  rising 
areas  of  volcanic  activity ;  it  should  also  be  stated  that  the  sink- 
ing areas  on  the  margin  of  the  sea,  where  the  sands  are  deposited, 
sometimes  break  as  they  go  down,  and  fissures  are  formed  through 
which  lava,  scoria,  and  ashes  poiu-  forth :  so  that  there  are  land 
areas  of  volcanic  activity  and  ocean  areas  of  volcanic  activity. 

Then,  again,  lands  which  have  ceased  to  rise,  and  have  been 
degraded  to  the  level  of  the  sea,  often  become  areas  of  depres- 
sion, and  go  down  below  the  level  of  the  sea ;  while  old  sea  bot- 
toms that  have  ceased  to  sink  appear  slowly  above  the  surface 
of  the  water  and  become  dry-land  areas,  and  in  turn  are  elevated 
into  plains,  plateaus,  and  mountains,  where  fissures  ai"e  formed, 
and  volcanoes  are  built,  and  rains  and  rivers  carve  out  valleys 
and  leave  hills  and  mountains.  So  land  areas  lieeome  sea  areas, 
and  sea  areas  become  land  areas,  until  the  processes  are  once 
more  reversed. 

Kinds  of  Rock. — It  has  alreadj'  been  seen  how  fissures  are 
formed  in  the  rock  envelope,  and  how  vents  are  produced  which 
become  chimueys,  throiTgh  which  molten  matter  is  poured  out 
upon  the  surface,  and  piled  uji  from  time  to  time  by  many  floods, 
until  volcanic  mountains  are  produced  whose  chimneys  open  to 
the  sky  in  gi-eat  funnel-shaped  craters.  Thus  a  volcanic  mountain 
is  composed  of  many  sheets  of  lava  that  have  been  poui'ed  out 
from  time  to  time  through  its  histoiy.  Rome  volcanoes  are  still 
active,  b^^t  many  have  ceased  to  emit  their  floods  of  fire,  and  dead 


V2  PHYSIOGRAPHIC  PROCESSES. 

voleauoes  iu  vast  numbers  are  scattered  over  various  portions  of 
the  globe. 

Volcanoes  do  not  always  emit  floods  of  molten  rock:  they 
sometimes  explode,  and  throw  dust,  ashes,  and  scoria  high  into  the 
air,  which,  faUiug  to  the  earth,  are  piled  up  iu  formations  of  ti((f'. 
The  very  tine  dust  is  sometimes  drifted  by  the  winds  over  great 
regions  of  country  for  himdreds  or  even  thousands  of  miles; 
but  the  coarser  materials  soon  fall,  and  by  a  long  succession  of 
such  explosions  mountains  of  ashes  and  cinders  may  be  formed. 
In  volcanic  regions,  cones  of  such  cinders  are  common.  Some- 
times they  attain  great  size,  so  as  to  be  several  hundi-ed  feet 
liigli ;  and  they  are  usually  characterized  by  distinct  craters. 

Rocks  formed  of  lava  and  accumiUations  of  ashes  a-ud  scoria 
are  called  iyncoiis  rocks. 

Many  rocks  are  soluble,  so  that  the  rains,  streams,  and  waves 
dissolve  them.  This  soluble  material  is  chiefly  carried  into  the 
sea,  where  it  is  deposited  by  various  agencies.  The  saltuess  of  the- 
sea  is  caused  by  salt  which  is  washed  out  of  the  land  and  cariied 
into  it.  The  suspended  material  is  carried  into  lakes  and  into 
the  sea.  Thus  the  waters  grind  down  the  lands,  and  bear  them 
away  to  be  deposited  under  the  lake  and  ocean.  The  materials 
are  arranged  iu  layers,  thin  in  some  places,  thick  in  others. 
Very  fine  materials  make  thin  layers,  coarser  materials  make 
thicker  layers,  all  of  which  are  called  strata.  Now,  these  strata 
differ  in  constitution  iu  many  ways,  because  they  come  from 
different  streams,  which  collect  sands  and  clays  from  different 
regions  of  coimtry,  and  because  the  waves  that  tear  down  the 
shores  find  different  materials  iu  different  regions.  Then  all 
this  material  brought  down  to  the  mouths  of  rivers  and  into  the 
surf  is  assorted :  the  coarser  material  soon  drops,  the  finer  mate- 
rial is  carried  farther,  and  the  rock  material  held  in  solution  is 
spread  all  over  the  sea.  The  dissolved  materials  thus  spread 
far  and  wide  form  limestone  chiefl}',  the  very  fine  nuiterials  form 
day,  coarser  materials  form  sandstone,  and  very  coarse  matei-ials 
of  gravels  and  bowlders  form  conglomerate. 

j  Many  animals  live  in  the  lakes  and  seas ;  and  when  they  die, 
'  their  bones  are  deposited  in  the  forming  strata.  !Many  plants 
live  on  the  shores  and  in  the  waters ;  and  their  leaves  and  stems 
sink  into  the  mud,  to  leave  their  impressions,  and  sometimes  their 
tissues,  in  the  forming  rocks.  Plants  and  animals  live  on  the 
land,  whose  hard  parts  are  washed  down  by  the  streams,  to  be 


SEDIMENTARY   ROCKS.  13 

bui'ied  ill  the  waters,  and  leave  their  remains  in  the  rocks.  Even 
the  bones  of  the  birds  of  the  air  are  buried  in  this  manner.  All 
such  fragments  of  life  entombed  in  the  rocks  arc  known  na  fos- 
sils. Above  the  marshes  and  shallow  waters  of  lake  and  sea 
there  is  a  rank  gi'owth  of  vegetation,  which  falls  after  matiu'ing 
from  year  to  year,  aii<I  is  overwhelmed  by  the  waters.  As  the 
years  go  by,  generation  after  generation  of  plants  live,  die,  and 
sink  below  the  waters,  until  great  accumulations  of  such  vege- 
table matter  are  formed,  constituting  jwaf.  ^Vlien  afterward 
this  peat  is  l)uried  l)y  sands  and  clays  and  gravels,  it  is  slowly 
transformed  into  coal,  and  thus  originate  the  coal  beds  found  in 
the  rocks.  The  leaves  in  these  rocks  afterward  tell  the  stoiy  of 
the  life  which  existed  at  the  time  the  rocks  were  formed. 

All  of  these  beds  of  limestone,  clay,  sandstone,  and  conglom- 
erate, are  laid  down  in  nearly  horizontal  strata  when  first  de- 
posited, or  they  incline  very  gently  away  from  the  shores.  As 
strata  are  accumulated  in  the  l)0(lies  of  water  in  the  manner 
above  descril^ed,  one  sti-atum  is  jiiled  on  another  until  a  numlter 
are  formed,  so  that  they  accumulate  in  tens,  hundreds,  and  thou- 
sands of  feet.  In  some  places  they  have  accumulated  to  a  thick- 
ness of  more  than  fifty  thousand  feet,  but  such  great  accumula- 
tions are  rare.  Accumulations  of  ten  or  twenty  thousand  feet 
are  quite  common.  As  the  strata  pile  up  in  this  manner,  the 
lower  members  ai-e  hardened  or  indurated. 

We  have  thus  found  two  kinds  of  rocks, —  igneous  rocks, 
which  have,  been  poui'ed  from  the  interior  of  the  earth  or  blo\vn 
out  by  explosive  forces;  and  sedimenfdri/  rocks,  which  have  been 
deposited  in  lakes  and  seas.  A  third  class  must  be  recognized, 
which  is  very  abundant  over  the  sui'face  of  the  earth,  and  out 
of  which  the  soils  are  made.  The  hard  rocks  below  are  dis- 
integrated by  atmospheric  agencies,  broken  up  by  heating  and 
cooling,  dissolved  to  some  extent  by  the  waters,  and  disin- 
tegrated and  changed  in  various  ways  by  chemical  agencies. 
This  disintegrated  material  is  washed  down  by  the  rains,  and 
gathered  by  the  rills,  brooks,  creeks,  and  rivers.  Much  more  is 
washed  down  by  the  rills  than  is  carried  by  the  brooks,  much 
more  is  carried  by  the  brooks  than  is  carried  by  the  creeks, 
and  much  more  by  the  creeks  than  by  the  rivers.  So  the 
disintegrated  rocks  are  strewn  from  liiglier  to  lower  lands,  and 
Ijiled  up  in  this  manner  as  bowlders  and  angular  fragments,  and 
as  sands  and  clays,  all  commingled  in  many  ways ;  so  that  the 


14  PHYSIOGRAPHIC  PROCESSES. 

lowlands  have  a  gi'eat  overplacemeut  of  these  rock  materials, 
which  are  not  eousolidated  like  the  rocks  deposited  uuder  the 
waters,  but  lie  ou  the  surface  of  the  laud  as  comparatively  loose 
material.  The  larger  streams,  as  creeks  aud  rivers,  have  low 
valleys  called  j>/fl/«s.  These  streams  have  theu*  chauuels  more 
thau  filled  by  great  raius,  aud  the  floods  stretch  over  the  ad- 
jaoeut  lauds.  AVherever  these  floods  reach,  a  plaiu  is  formed, 
kuown  as  a  flood  plain,  which  is  built  up  here  aud  there,  aud 
broken  dowu  agaiu  here  aud  there ;  so  that  the  overplaeed  uia- 
terials  brought  dowu  by  the  floods,  aud  deposited  outside  of  the 
chauuel,  are  coustautly  chaugiug  from  j)oiut  to  poiut. 

The  sands  that  are  formed  by  the  disiutegi'atiou  of  the  rocks 
over  the  surface  of  the  laud,  aud  by  the  beating  of  the  waves 
agaiust  the  shore,  are  drifted  by  the  winds.  When  the  tides  of 
the  sea  ebb,  gi'eat  stretches  of  naked  sand  are  left  bare ;  and  the 
winds  drift  the  sands  alongshore  out  to  sea,  aud  far  back  over 
the  laud,  sometimes  in  gi-eat  hills  and  ridges.  The  sands  of  the 
dry  laud  of  arid  regions  are  drifted  in  this  manner,  aud  are  often 
l)iled  into  hills  aud  ridges,  which  slowly  travel  before  prevailing 
winds.     Such  moving  hills  are  known  as  dunes. 

Ice  is  accumulated  ou  high  mouutaius  and  in  high  latitudes, 
and  it  moves  down  the  slopes  and  along  the  gorges  and  vallej's, 
plowing  its  way  over  rocks,  and  carrying  into  its  body  sands  and 
bowlders.  Thus  loaded,  it  becomes  an  agency  of  corrasion,  and 
excavates  the  valleys  and  polishes  the  hillsides,  until  it  reaches  a 
region  so  low  that  the  ice  melts,  ami  the  detritus  which  it  carries 
is  thro^vn  down  in  irregular  ridges  and  piles,  fi>rmiug  moraines. 

All  of  these  materials  may  be  called  tnanfle  rocks  or  super- 
ficial deposits.  They  are  still  called  rocks,  though  rarely  con- 
solidated into  hard  beds.  They  are  the  rocks  distributed  by 
gi-adation  over  the  land  as  distinguished  from  the  sedimentary 
rocks  that  are  deposited  on  the  bottoms  of  seas  and  lakes.  Thus 
there  are  two  great  classes  of  rocks  due  to  gradation, —  sedimen- 
tary aud  mantle  rocks. 

Plauts  grow  on  the  mantle,  which  is  scattered  over  all  the 
land ;  and  as  they  gi'ow  they  die  and  decay  aud  stain  it  black  at 
the  surface,  or  tliev  are  burned  and  their  ashes  discolor  the  rocks. 
This  staiued  mantle  rock  is  called  soil. 

And  still  a  fourth  class  of  rocks  must  be  recognized.  "We  have 
seen  how  rocks  are  upheaved  and  thrown  dowu  by  causes  not  yet 
fully  understood.    In  this  manner  great  regions  are  uplifted  above 


STRUCTURE  OF  THE  ROCK  ENVELOPE.  15 

the  sea-level,  aud  other  regions  are  displaced,  so  that  the  sea  flows 
over  them.  Then  we  have  seen  how  the  interior  rocks  are  poured 
out  as  molten  lava.  By  boring  into  the  rooks,  and  by  deep  mining, 
it  is  found  that  the  temperature  of  the  rock  crast  increases 
from  the  surface  downward  at  about  the  rate  of  1°  Fahrenheit 
to  every  fifty  or  seventy-five  feet,  as  this  increase  of.  temperature 
is  somewhat  variable.  Now,  when  rocks  are  doei)ly  buried,  they 
are  subject  to  great  pressure  from  the  overlying  strata,  aud  they 
are  greatly  heated  at  depths  of  many  thousand  feet.  They  are  also 
broken,  flexed,  contorted,  aud  twisted  as  the  land  goes  up  and 
down ;  and  by  all  these  processes  sedimentary  rocks  and  igneous 
rocks  alike  are  changed  in  both  chemical  and  crystalline  struc- 
ture. The  gi-ains  of  sedimentary  rocks  are  obscured,  or  often 
entirely  changed  into  crystals;  and  the  volcanic  rocks  which  have 
one  crystalline  form  when  they  cool,  have  anotlier  ciystalline 
form  after  they  have  been  changed  by  this  method.  All  sucli 
rocks  are  known  as  ntctdinurphir. 

We  must  therefore  recognize  four  great  i-lasses  of  I'ocks,  — 
volcanic  or  igneous  jocks,  sedhnentari/  ,ov  clastic  rocks,  mantle  or 
superficial  rocks,  and  »u'fa»iorp]tic  or  changed  rocks/ 

Structure  of  the  Rock  Envelope. — The  upheaval  and  sub- 
sidence of  the  rock  enveloi)e  is  very  irregular  in  time,  in  place, 
and  in  manner.  Some  regions  of  country  have  been  subject 
through  long  geological  ages  to  alternate  upheaval  and  subsi- 
dence on  a  great  scale,  so  that  the  total  upheaval  may  be  many 
thousands  of  feet,  while  the  movements  of  subsidence  may  be 
many  thousands  of  feet.  There  are  other  regions  where  such 
movements  are  better  measured  by  hundreds  of  feet,  and  still 
others  by  scores  of  feet. 

All  of  these  movements  are  very  slow,  occurring  through  thou- 
sands of  years.  In  some  regions  the  process  is  gradual,  so  that 
the  roctks  are  flexed;  in  other  regions  the  process  is  intermittent, 
the  rocks  seeming  graduallj^  through  long  centuries  to  accumulate 
a  strain,  nntil  at  last  they  yield  by  rupture,  and  rise  or  fall  ahnig 
the  rupture  pianos;  then  the  strata  of  one  sidi^  lie  higher  than 
those  of  the  other.  Displacements  of  this  kind  are  known  as/aults. 
Thus  there  is  displacement  by  flexure,  and  displacement  by  faiilt- 
ing.  Faulting  displacement  seems  always  to  canse  earth(|uakes. : 
Displacement  by  faulting  seems  to  be  more  common  than  displace- 
ment by  flexing,  at  least  so  far  as  the  world  has  been  studied  by 
geologists.    In  gi*eat  displacement  by  faulting  and  flexing,  regions 


16 


PHYSIOGRAPHIC   PEOCESSES. 


of  rock  are  separated  into  bloeks  which  greatly  vary  in  size  aud 
shape  from  district  to  district.  As  the  beds  are  hvid  down  by 
the  water,  or  jjoured  out  by  erui)tion  from  the  interior,  they  are 
formed  in  layers — some  very  thin,  like  leaves  of  paper;  others 
thicker — imtil  some  are  gi'eat  beds  tens  of  feet  in  thickness.  The 
bods  thus  laid  down  are  broken  by  displacement  into  small  blocks 
by  transverse  fractures,  antl  are  said  to  be  jointed.  There  are 
great  regions  where  such  joints  are  abundant,  with  rocks  broken 
into  blocks  only  a  few  inches  square,  while  elsewhere  they  may 
be  in  large  blocks  many  yards  square.  So  far  as  it  is  known, 
the  entire  rock  envelope  is  broken  into  small  blocks  in  this 
manner. 

It  has  been  shown  that  most  rocks  are  oritjinallv  forined  as 
horizontal  beds ;  Imt  by  displacement  through  upheaval  aud  sub- 
sidence, when  the  rocks  are  faulted  or  flexed,  these  horizontal 
beds  are  tilted  in  great  regional  Ijlocks  hundreds  or  thousands  of 
square  miles  in  extent,  so  that  in  many  regions  we  find  the  beds 
of  rock  inclined,  and  they  are  said  to  dip  in  the  dii-ection  in 
which  they  are  turned  down.  In  many  places  the  blocks  are 
gently  inclined  in  this  manner ;  but  in  many  others  the  inclina- 
tion is  great,  aud  the  rocks  are  found  to  be  dipping  at  an  angle 
of  more  than  45° ;  while  in  many  other  cases  the  strata  of  the 
blocks  stand  on  their  edges,  and  the  dip  is  vertical ;  and  yet  more, 
in  i-arer  cases  the  lilocks  are  overturned  in  such  a  manner,  that 
the  first-formed  rocks  lie  on  top,  that  is,  the  blocks  have  been 
turned  more  than  90°. 

A  region  of  country  composed  of  blocks  diiiping  in  various 
directions,  and  at  different  angles,  may  be  washed  down  to  the 


^^mm^^^^^ 


^^ik 


''WWmmmm^ 


Dia^'i-am  of  Viu'nnfoviiialile  Strata. 


level  of  the  sea,  and  then  may  slowly  sink  beneath  the  sea,  and 
become  a  region  of  sedimentation,  where  rocks  are  once  more 
accumulated.    These  new  rocks  are  laid  down  in  IxhIs  which  are 


OMGIN   OF   OEE  DEPOSITS. 


17 


practically  horizontal,  upon  a  floor  of  beds  which  are  dipping  in 
various  directions  and  at  various  angles.  In  tliis  manner  the 
newly  formed  beds  will  not  oonforiu  with  the  earlier  strata:  that 
is  what  the  geolouist  calls  uiiconformit[i. 


Uneonfonuitv  as  seeu  in  Natvire. 


To  understand  unconformity,  put  a  dozen  or  twenty  thin 
books  on  your  table  side  by  side,  with  the  backs  uj^permost; 
then  place  other  books  on  the  top  of  these,  the  top  books  with 
their  flat  sides  next  to  the  edges  or  backs  of  the  fii-st  series ;  con- 
sider the  books  on  edge  as  a  series  of  rocks  dipping  at  an  angle 
of  90°,  and  the  books  on  top  as  a  series  of  rocks  lying  horizontal 
on  the  upturned  edges  of  the  lower  rocks.  You  will  tlien  under- 
stand what  the  geologist  means  when  he  says  that  he  has  dis- 
covered two  series  of  rocks,  one  of  which  is  unconformable  to 
the  other.  It  is  not  necessary  that  the  first  books  should  stand 
on  edge  (they  may  incline  at  any  angle);  but  if  the  upper  rocks 
have  one  inclination,  and  the  lower  rocks  anothei-,  there  is  said 
to  be  an  unconformity.  It  will  be  seen  that  sucli  an  xmconform- 
ity  has  gi-eat  significance  in  geologic  history.  The  rocks  below 
were  formed  at  one  time,  and  the  rocks  above  at  another  and 
later  time ;  but  these  times  were  separated  by  a  dry-land  jjci-iod 
of  upheaval  and  degradation  which  may  have  been  very  long. 

Ores. — Now,  the  rocks,  as  they  are  laid  down  by  water  and 

poured  out  from  the  interior  of  the  earth,  contain  iron  and  nianj^ 

i  other  metals.    As  the  waters  percolate  down  the  fissures,  they 

dissolve  the  metals  and  other  substances,  and  redeposit  them  in 


18  PHYSIOGRAPHIC  PROCESSES. 

the  fissures  as  ores.  Sometimes  these  fissures  come  to  be  veiy 
wide, —  many  inches  or  even  many  feet  across, —  but  as  they 
open,  they  are  tilled  with  ores  by  the  percolating  waters.  Usually 
the  fissures  do  not  open  completely  by  one  movement,  but  open 
gi-adually  from  time  to  time ;  and  when  they  thus  open,  they  are 
displaced,  that  is,  there  is  a  vertical  movement  along  the  plane 
of  fracture.  There  are  thus  two  irregular  walls ;  and  as  the  move- 
ment goes  on,  the  projections  in  these  walls  hold  them  apart,  and 
the  width  of  the  fissures  increases  with  the  depth  of  the  displace- 
ment. With  every  change  occurring  in  this  manner  the  fissure 
increases  its  width,  and  new  deposits  of  ore  are  formed  to  fill  the 
vacant  spaces.  Thus  the  ores  often  have  a  lamellar  or  leaf  struc- 
tiu'e  corresponding  more  or  less  Avith  the  walls  of  the  fissure. 

Such  fissures  and  displacements  occur  more  abundantly  in 
regions  of  volcanic  activity,  where  the  waters  are  heated  by  the 
hot  rocks,  and  their  chemical  activity  increased  by  the  higher  tem- 
perature. This  action  of  hot  waters  is  known  as  solfataric  action, 
and  solfataric  waters  are  quite  common  in  volcanic  regions. 

Many  of  the  rocks,  especially  limestones,  are  highlj'  soluble, 
and  such  may  be  placed  between  beds  of  insoluble  rocks.  Under 
these  circumstances,  where  conditions  are  favorable,  the  soluble 
rocks  wiU  be  carried  away  by  percolating  solvent  waters :  and  as 
fast  as  they  are  removed,  they  may  be  replaced  by  various  ores. 
Siich  ore  beds  are  common,  and  often  of  great  value  by  reason  of 
the  great  quantities  of  ores  derived  from  them. 

Again,  ore  deposits  are  often  found  in  unconformities.  Iron 
is  often  deijosited  as  a  bog  ore  in  unconformities.  Such  ores 
may  ultimately  be  covered  by  sedimentary  rocks.  Again,  in 
such  unconformities  percolating  waters  carry  away  the  soluble 
materials,  and  leave  behind  the  ores  of  metals ;  so  that  deposits 
of  ores  are  common  in  unconformities.  As  the  subject  of  ore 
deposits  is  one  of  gi'eat  magnitude,  it  is  not  uecessaiy  that  it 
should  receive  full  treatment  in  this  place ;  but  what  has  l:)een 
said  may  be  summed  uj?  in  the  statement  that  ores  are  found  in 
great  abundance  in  veins  formed  in  fissures,  that  they  are  formed 
in  beds  where  they  have  replaced  soluble  rocks,  and  that  they 
are  discovered  in  gi'eat  unconformities. 

Age  of  Rocks. — From  the  pre\-ious  explanations  of  the  re- 
gion it  will  be  clear  to  the  student  that  rocks  may  be  of  diflferent 
ages,  —  that  some  were  f onned  a  very  long  time  ago,  some  but 
lately,  and  others  are  forming  now.     One  of  the  great  subjects 


AGE    OF   KOCKS.  19 

of  iuvestigatiou  that  geologists  imdertake  is  that  of  determiuiug 
the  age  of  the  rocks.  This  research  has  beeu  carried  on  iu 
many  lands  by  many  men,  so  that  much  is  known  about  the  age 
I  of  rocks.  The  oldest  rocks  are  known  to  be  many  millions  of 
years  old,  but  how  many  millions  cannot  yet  Ije  decided.  From 
the  formation  of  the  oldest  rocks  to  the  present,  the  time  is  very 
long.  This  time  has  Ijeen  divided  by  geologists  into  periofls,  and 
the  periods  again  subdivided;  ))ut  for  the  present  pm'pose  it  is 
only  necessary  to  consider  the  grand  periods  into  which  geologic 
time  is  divided. 

1       The  oldest  rocks  known  are  called  Anlican.     In  them  no 
'fossils  are  found.     The  period  of  their  deposition  is  called  the 
Arcliean  period. 

The  next  period  in  succession  is  called  AJfioiihiioi.  \^\  the 
rocks  formed  during  this  age  no  well-defined  fossil  forms  have 
been  found,  and  yet  there  are  evidences  that  life  existed. 

Following  the  Algonkian  i)eriod  is  the  Carnhndu,  in  which 
fossils  are  found  with  well-defined  forms ;  but  tliey  all  prove  to 
be- remains  of  animals  of  very  simple  and  low  structure. 

Then  follows  the  Silurian  period.  The  rocks  formed  in  Silu- 
rian time  contain  many  nioi-c  kinds  of  fossils  than  the  rocks  of 
Cambrian  time;  and  their  remains  show  that  these  animals  were 
some  of  them  of  low  structure,  as  in  Cambrian  time,  but  that 
others  were  of  much  higher  forms. 

Then  follows  the  Dcroiiiuit,  period,  with  a  still  ginuiter  number 
of  kinds,  and  among  them  still  higher  forms. 

Then  follows  the  Carhoniferous  period,  with  evidences  of  plant 
and  animal  life  still  more  varied,  witli  forms  still  moi'e  highly 
developed. 

Then  succeeds  Wn'.  Jiinitiidti  jH'i'iod,  with  life  forms  still  more 
highly  developed. 

Then  follows  the  Crcfdceous  period,  with  more  liighlv  evolved 
life. 

Then  follows  the  J£ocene  period,  with  yet  more  highly  evolved 
life. 

Then  the  Neocene  period,  with  fossU  life  more  varied  and 
more  developed  tlian  ever  before. 

Finally  wo  reach  the  rieisfoeeiic  period,  which  includes  tlie 
present  time.  In  this  period  the  mantle  rocks  have  ln'cu  formed, 
while  lake  and  ocean  deposits  have  been  made  during  the  same 
time. 


20  PHYSIOGRAPHIC  PROCESSES. 

Tims  we  liave  the  following  table  of  periods,  the  last  period 
at  the  top  of  the  column  : — 

Pleistocene, 

Neocene, 

Eocene, 

Cretaceous, 

Juratrias, 

Carboniferous, 

Devonian, 

Silurian, 

Cambrian, 

Algonkiau, 

Archean. 

From  Land  to  Sea,  and  Sea  to  Land. — Displacement  by 
faulting  and  flexing  plays  a  very  important  part  in  determining 
the  ]ihysioal  characteristics  of  the  land.  If  there  were  no  uji- 
heaval,  the  rains  and  streams  would  degrade  all  the  lands  to 
the  level  of  the  sea,  and  all  islands  and  continents  would 
become  vast  marshes.  But  for  displacement,  there  would  be  no 
volcanic  or  exjilosive  eruption :  so  even  the  volcanic  mountains 
would  disappear.  By  displacement  deep  basins  are  formed  in 
the  rock  envelope  which  holds  the  seas  and  great  lakes,  while, 
at  tlie  same  time  dry  lauds  are  formed.  But  these  di-y  lauds  are 
l>roken  with  faults  into  great  blocks  hundreds  and  thousands  of 
sqiiare  miles  in  extent,  and  are  tilted  in  various  dii-ections ;  other 
regions  are  flexed  or  bent  into  great  wrinkles ;  and  still  other  I'e- 
gions  are  in  part  faulted,  and  in  part  flexed.  All  dry  lands  are 
brought  above  the  level  of  the  sea  by  displacement  and  igneous 
action ;  and  as  soon  as  they  become  dry  lands,  the  rains  fall  upon 
them,  and  carry  them  away.  It  is  thus  that  the  lands  are  pri- 
marily due  to  upheaval  and  igneous  action.  Then  their  surfaces 
are  modeled  by  rains  and  streams,  which  are  the  great  sculptors, 
candng  valleys,  and  embossing  the  hills  and  mountains. 

The  altitude  of  the  region  of  country  above  the  level  of  the 
sea  is  the  difference  between  the  amount  of  upheaval  and  the 
amount  of  degi-adation  liy  the  waters.  The  upheaval  may  h-ave 
been  hundreds  or  thousands  of  feet,  whili^  the  degradation  is 
always  less  if  dry  land  remains.  The  upheaval  is  always  an 
irregular  warping,  with  flexures  and  faults  on  a  grand  scale ; 
the  degi-adation  is  always  an  irregular  car-ving  by  rains,  liUs, 


EXPOSUKE   OF   OLDER 'kOCKS.  21 

brooks,  creeks,  and  rivers,  aided  by  the  beating  of  the  waves 
against  the  shores.  Where  the  rivers  run,  the  degradation  is 
rapid,  for  the  great  streams  carve  deep  and  wide  cliannels;  and 
these  channels  are  narrower  and  more  sliallow  wliere  the  trib- 
utary streams  come  down,  the  channels  becoming  less  and  less 
as  the  streams  divide  again  and  again,  until  they  disappear  in 
liillside  rills.  The  upheaval  of  the  land  by  displacement,  and 
the  Ijuilding  of  the  land  ))y  volcanic  activity,  are  the  methods  l)y 
which  the  lands  are  brought  above  the  level  of  the  sea ;  and  the 
carving  of  these  dry  lands  by  water  is  the  method  by  which 
physiographic  features  are  produced. 

Man  is  enabled  to  study  rocks  as  they  are  exhibited  in 
stream  banks,  in  the  quarries  of  hillsides,  in  the  faces  of  cliffs,  in 
wells  and  in  deep  mines.  In  this  manner  he  is  enabled  to  see 
something  more  than  the  alluvial  rocks  at  the  sui'faco.  The 
deepest  borings  and  mines  are  rai'cly  more  than  a  tVnv  liuiidred 
feet,  though  there  is  an  occasional  mine  or  boring  which  reaches 
down  for  a  few  thousand  feet.  Then  we  can  study  I'ocks  which 
come  from  below  through  volcanic  vents.  But  the  geologist  may 
study  rocks  that  have  at  one  time  been  very  deep  in  the  crust, 
and  have  since  been  upheaved,  and  the  overlying  rocks  carried 
away  by  water;  so  that  it  is  not  uncommon  for  the  geologist  to 
see  rocks  which  he  knows  have  been  buiied  in  former  times  to 
a  depth  of  thousands  of  feet,  and  he  is  sometimes  abh^  to  exam- 
ine rocks  which  he  knows  were  originally  deposited  from  forty 
to  sixty  thousand  feet  below  their  present  altitude.  It  is  by  all 
these  conditions  that  the  structure  of  the  rock  envelope  is  re- 
vealed. 

In  a  great  mountain  range  the  crust  may  have  been  wrinkled 
in  one  great  flexure  extending  along  a  line  hundreds  of  miles  in 
length,  the  flexure  spreading  from  the  central  line  of  u]iheaval 
for  tens  of  miles.  This  great  i)lain  may  have  been  ui>lifted  in  its 
central  portion  forty  thousand  feet  or  more,  while  the  rains  may 
have  carried  away  from  the  crest  perhaps  thirty  thousand  feet  or 
more  of  the  rocks.  So,  in  passing  from  the  foot  of  the  mountain 
up  toward  its  crest,  the  geologist  walks  over  the  upturned  edges 
of  the  strata,  and  studies  them  in  succession,  and  measures  their 
thickness,  and  collects  from  them  the  fossils  which  they  contain, 
from  bed  to  bed,  as  he  goes  uji  the  mountain  geograi>hically,  but 
flnds  rocks  that  contain  forms  of  lower  life.  As  he  changes  his 
view  from  the  later-formed  strata  in  the  valleys  to  the  earlier- 


22  PHYSIOGRAPHIC   PKOCESSES. 

formed  strata  at  the  mountain  summit,  he  roAiews  the  history  of 
the  plants  and  animals  that  succeeded  from  a  primeval  life  to  the 
life  of  the  present  time. 

It  is  thus  that  the  geologist  is  enabled  to  review  in  one  day's 
walk  a  panorama  of  the  history  of  millions  of  years.  As  he  walks, 
he  may  pass  over  beds  of  ancient  shells,  and  find  the  bones  of 
ancient  animals,  and  discover  the  site  of  ancient  coral  reefs,  and 
tread  on  the  rocks  of  ancient  shores,  and  find  the  plants  of  ancient 
forests,  and  at  the  same  time  gaze  on  canyons  carved  by  mighty 
rivers,  OA'erlook  valleys  carved  by  glaciers,  and  watch  the  clouds 
play  among  the  cirques  and  pinnacles  of  towering  mountains. 

IN'TERPENETKATION  OF  THE  ENVELOPES. 

The  envelopes  of  air,  water,  and  rock  are  so  distinct  that  they 
can  be  clearly  distinguished;  and  yet,  when  they  are  carefully 
studied,  it  is  discovered  that  every  one  encroaches  upon  the  ter- 
ritory of  the  others,  not  only  by  interaction,  but  also  by  inter- 
penetration.  It  has  already  been  shown  that  the  water  pene- 
trates deep  into  the  rock.  Every  sjiriug  that  falls  from  a  hillside 
gives  proof  that  the  rocks  above  its  level  hold  water,  which  they 
j'ield  slowly  as  a  perennial  supply;  and  the  innumerable  hills  of 
the  continents  and  islands  have  their  innumerable  springs.  Everj- 
well  proves  that  there  is  water  below;  every  artesian  fountain 
shows  the  existence  of  undergi-ouud  waters;  and  every  boring  in 
the  crust  of  the  earth,  and  every  excavation  in  uudergi-ound  min- 
ing, discovers  the  jiresence  of  water. 

Wherever  water  flows,  air  flows  with  it,  and  all  natural  waters 
are  permeated  with  air. 

The  aqueous  envelope  is  everywhere  permeated  with  rock, 
which  it  holds  in  solution  or  suspension,  and  there  is  no  natural 
water  absolutely  jnu'e.  The  sea  is  full  of  salt.  Halt  lakes  are  more 
than  full  of  salt,  and  so  they  must  throw  it  upon  the  bottom ;  and 
the  waters  hold  lime  and  many  other  sulistances.  Not  a  drop  of 
pure  water  can  be  found  in  the  sea;  not  a  drop  can  be  found  in 
a  lake ;  not  a  di'op  of  pm*e  water  can  be  found  in  any  river,  creek, 
brook,  or  spring;  and  not  a  drop  of  pure  water  can  be  found  >un- 
dergi-ound :  it  is  all  mixed  to  some  degree  with  rock. 

All  natural  waters  are  aerated.  No  drop  of  water  unmixed 
with  rock  and  air  can  be  found,  except  by  the  process  of  artificial 
purification. 


\ 


VULCANISM,   DIASTROPHISM,   AND   GRADATION.  23 

But  surely  there  is  pure  ah-  ?  Nay,  not  so.  There  is  no  natu- 
ral air  unmixed  with  rock  and  water.  All  the  air  which  circu- 
lates above  the  laud  and  sea,  within  the  ken  of  man,  and  all  the 
air  which  circulates  underground,  is  mixed  with  rock  and  water. 

Pure  air  is  invisible :  it  will  not  reflect  light ;  it  is  transparent, 
but  will  not  convey  light.  Light  is  conveyed  through  the  atmos- 
phere by  ether,  and  is  reflected  and  refracted  by  rock  and  water; 
and  it  seems  to  be  largely  affected  in  this  manner  by  rock.  If 
the  ambient  air  of  the  earth  were  pure,  there  Avould  be  no  color 
in  the  sky,  no  rainbow  in  the  heavens,  no  gi'ay,  no  purjile,  no 
crimson,  no  gold,  in  the  clouds.  AU  these  are  due  largely  to  the 
dust  in  the  air.  The  purple  cloud  is  painted  with  dust,  and  the 
sapphire  sky  is  adamant  on  wings. 

Land  plants  live  on  undergi-ound  waters :  were  there  no  sul)- 
terranean  circulation  of  water,  there  would  be  no  land  plants. 
Fishes  live  on  under-water  au- :  were  there  no  cu-culation  of  sub- 
aqueous air,  there  would  be  no  fishes  in  the  sea.  The  clouds  are 
formed  by  particles  of  dust  in  the  air,  which  gather  the  vapor : 
were  there  no  dust  in  the  air,  there  would  be  no  clouds ;  were 
there  no  clouds,  there  would  be  no  rain. 

VULCANISM,  DIASTROPHISM,  AND   GRADATION. 

From  what  has  hitherto  been  said,  it  will  be  jilain  to  the  reader 
that  there  are  two  grand  physiographic  changes  by  which  the 
forms  or  f eatm-es  of  the  land  surfaces  of  the  earth  are  produced,  — 
one  by  which  the  land  goes  up  and  down,  that  is,  by  vei'tical 
change;  and  the  other  by  which  the  land  is  transported  from 
one  district  to  another,  that  is,  by  horizontal  change. 

The  vertical  changes  are  produced  by  two  processes.  By  one, 
materials  from  the  interior  of  the  earth  are  bi-ought  uji  to  its 
surface.  This  may  be  called  rnlcanisin,  and  we  liave  volcanic  pro- 
cesses. By  the  other,  regions  sink,  and  regions  rise,  and  the  up- 
heaval and  subsidence  may  be  called  diasfrophisni,  and  we  liave 
diastrophic  processes.  The  horizontal  movements  consist  in  the 
transportation  of  materials  from  one  region  to  another,  generally 
by  the  agency  of  water,  but  to  some  slight  extent  by  the  agency 
of  wind,  and  to  a  very  slight  extent  by  the  agency  of  life,  for  the 
animals  build  up  materials  of  the  earth  into  their  tissues,  and 
transport  them  from  place  to  place ;  but  for  our  piu'pose  we  may 
neglect  life  agency  and  wind  agency,  and  consider  only  the  aque- 


24  PHYSIOGRAPHIC   PROCESSES. 

ous  agency.  By  aqueous  ageucy  the  rocks  are  degraded  from 
one  region  and  transported  to  another,  and  there  built  up  or 
constructed  into  new  forms.  This  may  be  called  fjradation,  and 
we  have  grading  processes.  Hence  we  have  to  consider  vol- 
canic processes,  diastrophic  processes,  and  grading  processes. 

VuLCANiSM. — By  volcanic  processes  materials  are  brought 
from  a  gi'eat  depth  to  the  surface,  when  they  are  said  to  be  cr- 
trmled;  and  sometimes  they  are  brought  from  great  depths  and 
left  still  within  the  crust,  filling  crevices,  or  pushed  laterally  be- 
tween layers  of  the  crust:  then  the  lavas  are  said  to  be  lutrnded. 
Of  that  which  comes  to  the  surface,  a  large  part  is  in  a  molten  or 
fluid  form ;  but  another  almost  as  large  part  comes  out  as  frag- 
ments thrown  up  by  explosions.  The  lavas  that  are  poured  out 
form  coulees,  or  sheets  of  rock,  when  they  are  cooled,  and  often 
one  is  piled  on  another;  and  sometimes  vents  are  produced  which 
are  kept  open  for  a  long  time,  or  periodically  are  closed,  so  that 
there  may  be  a  continuous  or  an  intermittent  pouring  of  lava. 
Sometimes  the  melted  lava  is  sent  to  the  smi'ace  and  high  into 
the  air  by  explosive  action  :  cinders  are  therefore  lavas  that  have 
been  extruded  l)y  explosion  while  yet  molten. 

Some  lavas  extruded  by  explosion  come  out  in  the  form  of 
fine  dust,  as  if  the  explosive  agency  had  thoroughly  pei'meated 
the  lava  itself ;  and  when  the  explosion  comes,  it  is  torn  into  the 
most  minute  fragments,  constituting  an  impalpable  ash.  Be- 
tween dnst  or  ash,  cinders  or  scoriae,  and  sheets  of  lava  or 
coulees,  no  distinct  demarcation  can  be  made :  they  gi'ade  into 
one  another.  From  the  finest  dust  there  ai'e  gradations  into 
cinders,  and  from  the  cinders  there  are  gradations  into  coulees; 
and  yet  the  dust  is  sent  into  the  air  as  fragments  of  ash,  and  the 
coulees  come  to  the  surface  in  flowing  streams. 

The  coulees,  cinders,  and  ashes  come  from  the  interior  inter- 
mittently. In  a  great  region  of  country,  like  that  of  the  Eocky 
Mountains  or  of  the  Andes,  an  eruption  occurs  at  one  time  and 
then  at  another,  and  at  one  place  and  then  at  another.  Usually 
the  irregularity  of  place  is  very  great;  so  that  large  areas  of  coun- 
try are  subject  to  volcanic  activity,  and  have  sheets  of  lava  spread 
over  them — now  here,  now  there — from  time  to  time.  But  oc- 
casionally the  eruption  is  concentrated  for  a  long  time  at  one 
point,  so  that  eruption  follows  eruption  from  one  vent,  and  then 
volcanoes  are  produced;  but  the  more  common  process  forms 
only  volcanic  plateaus  of  very  irregular  outline.     Enough,  per- 


DIASTROPHISM. 


25 


A  ( Viuleu  (if  Liiva. 


haps,  has  been  said  to  make  it  i^lcar  liow  the  hind  is  l)iiilt  uj)  by 
vulcauism. 

DiASTEOPHlSM. — This  is  the  uplifting  and  subsidence  of  the 
earth's  crust.  Why  the  rot^k  env(^lope,  wliich  must  bo  of  onor- 
mous  weight,  is  really  moved  in  this  manner,  is  not  ■well  known  ; 
or,  at  any  rate,  no  scientific  man  has  explained  it  in  such  a  man- 
ner that  all  other  scientific  men  agree  with  him.  To  the  fact  of 
uplifting  and  subsidence  all  agree,  and  to  many  of  its  character- 
istics there  is  general  assent ;  but  no  complete  explanation  of 
this  cause  has  universal  acceptation.  We  are  therefore  under 
the  necessity  of  stating  some  of  tlie  facts  of  displacement  with- 


26 


PHYSIOGRAPHIC   PROCESSES. 


i 


out  properly  showing  theii'  causes.  It  is  well  known  that  the 
rocks  are  fractiu-ed  1  )y  iri-eat  fissures  miles  in  length,  or  scores  of 
miles  in  length,  or  even  hundreds  of  miles  in  length,  and  that 
along  these  fissures  the  rocks  are  displaced.  Sometimes  the  rocks 
go  down  or  up  on  one  side,  and  it  seems  that  there  are  times  when 
the  rocks  go  down  on  one  side  and  up  on  the  other  at  the  same 
time,  and  this  may  always  be  the  ease.  "When  rocks  are  displaced 
in  this  manner,  they  ai-e  said  to  hefaiilfed.  Small  faults  and  great 
faults  are  found  in  the  rocks.  The  amount  of  dis]tlacement  is 
called  the  ihroic;  and  the  throw  may  be  just  perceptible,  or  it  may 
be  thousands  of  feet.  In  some  cases  the  faults  may  be  but  a  few 
yards  in  length  ;  in  other  cases  they  may  be  hundreds  of  miles. 
Great  faults  are  never  made  at  one  movement,  but  by  inter- 
mittent smaU  movements  following  one  another  in  a  long  succes- 
sion. Sometimes  a  fault  which  is  single  for  a  distance  will  diWde 
into  two  or  more  fracti;res,  with  two  or  more  displacements; 
sometimes  there  is  a  series  of  parallel  faults,  so  that  the  entire 
disi^lacemeut  is  produced  by  a  series  of  steps.  As  the  faulting 
is  intermittent,  and  as  years  or  centuries,  or  centuries  of  centuries, 
may  intervene  between  movements,  great  change  may  be  wi'ought 
in  the  surface  along  the  faults  by  rains  and  rivers  cutting  out 
valleys  and  leaving  hills.  Then  from  time  to  time  lavas  may 
pom-  out  through  the  fissures,  and  flow  do"mi  into  the  vaUeys 
between  the  hills,  or  may  even  cover  up  the  hills;  and  when 
the  faulting  is  renewed,  the  lavas  themselves  are  fractured. 
Sometimes  these  lavas  form  obstructions  or  dams  in  the  valleys. 


Diagram  of  a  Fault. 


f  a  Moiioc'liiial  Flexure. 


and  the  waters  accumulate  therein,  and  sediments  are  washed 
into  tlu^  waters,  and  sedimentary  rocks  are  deposited  in  the  lakes 
over  the  fissm-es.  When  the  diastrophic  activity  is  renewed, — 
that  is,  when  the  faulting  again  occurs, — these  beds  are  broken. 
Regions  of  country  treated  in  this  manner  may  be  again  faulted 


FAULTS    AND    FLEXVRES. 


27 


by  parallel  fractures,  and  carved  into  valleys  and  hills,  and  cov- 
ered with  lavas  and  sedimentaiy  rocks,  and  broken  again  from 
time  to  time.  This  may  go  on  for  millions  of  years,  and  for  a 
long  distance,  say,  hundreds  of  miles.  The  total  effect  of  such 
a  series  of  displacements  will  make  the  country  on  one  side  of 
the  line  of  faults  very  much  higher  than  it  is  on  the  other ;  while 
the  rocks  uplifted  will  be  turned  up  so  that  they  dip  away  from 
the  faulted  zone. 

It  is  thus  that  we  sometimes  find  a  simple  fault  to  be  a  mere 
fracture,  with  a  single  displacement ;  while  at  other  times  we 
find  complex  fractures,  with  many  displacements,  and  a  long 
history  involved. 


;p#^v>--;S*';W"  \  J':^'^'9'f^^gm'?>li»'^i^"7^': 


^' 


A  Mouocliual  Flexiu'e  as  seen  in  Natui'e. 


The  same  amount  of  displacement  can  occur  under  very 
different  conditions.  Cut  a  sheet  of  paper  in  two,  and  arrange 
the  parts  on  your  tahle  so  that  one  of  the  cut  edges  lies  higlun* 
than  the  other,  say,  about  an  inch.  Tluni  bend  another  sheet 
of  paper  down  and  out  again,  so  that  on  one  side  of  the  bend  the 


28  PHYSIOGRAPHIC  PROCESSES. 

paper  is  an  incli  higher  than  ou  the  other.  By  the  two  methods 
you  luxve  made  two  kinds  of  displaceiuents,  —  one  by  faulting,  the 
other  by  flexing.  Now,  rocks  on  the  crust  of  the  earth  may  be 
beut  iu  this  manner,  and  such  bends  are  called  iiionocUiidl  Jicx- 
ures.  Both  forms  of  displacements  are  common,  but  faulting  is 
more  often  seen  than  flexing. 

A  series  of  parallel  monoeliual  flexures  of  this  kind,  not  very 
far  apart,  produce  a  series  of  wrinkles;  and  we  have  upturned 
wrinkles  and  dowiitunied  wrinkles.  The  upturned  wi'inkles  are 
called  a)iticU)i(tI,  and  the  downturned  wrinkles  tfijiicliiial.  Such 
anticlinals  and  synclinals  are  usually  called  folds,  and  so  we  have 
anticlinal  and  synclinal  folds.  Thus  displacement  is  represented 
by  faidts,  mouoclinal  flexures,  and  folds.  Faults  change  into 
monoeliual  flexures  sometimes  abruptly,  and  sometimes  grad- 
ually,— that  is,  the  tiisplacement  may  be  carried  on  for  a  time  as 
a  flexure,  and  suddenly  change  and  become  a  fault, — so  that  it  is 
impossible  to  draw  an  absolute  distinction  between  faults  and 
mouoclinal  flexu.res,  and  between  flexures  and  folds :  one  method 
of  displacement  ruus  into  another. 

The  crust  of  the  earth,  or  the  rock  envelope,  is  of  great  thick- 
ness, but  just  how  thick  is  not  known,  probably  several  miles ; 
and  these  faults,  flexures,  and  folds  are  found  to  extend  as  far 
down  as  man  is  able  to  study  the  condition  of  the  rocks.  It 
seems  probable  that  great  faults  extend  quite  through  what  is 
known  to  geologists  as  the  crust,  and  there  is  some  e^ddence  to 
show  that  often  that  which  appears  as  a  fault  at  the  surface,  ap- 
pears as  a  flexure  at  a  gi'eat  depth ;  but  this  is  a  generalization 
which  must  be  made  with  some  reservation,  because  observations 
have  not  been  can-ied  to  such  an  extent  as  to  warrant  the  state- 
ment that  si;ch  is  tlie  law. 

By  gi-eat  faults  and  flexures  the  crust  of  the  earth,  so  far  as 
it  is  known  to  man,  is  divided  into  great  regions  scores  or  even 
hundreds  of  square  miles  in  extent ;  but  each  of  these  parts  is 
again  broken  by  smaller  fractures  called  joints.  Sometimes  this 
shattering  is  very  minute,  sometimes  it  is  very  coarse ;  but  it  is 
usuallj^  more  or  less  regular,  so  that  the  blocks  are  broken  into 
somewhat  regular  forms.  Thus  it  is  that  the  wovkuuiu  in 
quarrying  rocks  never  finds  them  in  continuous  bodies,  but 
always  discovers  that  they  are  broken  into  blocks  of  greater  or 
less  extent. 

Perhaps  we  have  i^resented  already  all  that  is  necessary  on 


i^ 


K* 

X    ■ 

H-    ' 

>   \ 

he; 

r 

>.. 

\ 


/■ 


r 


w 


29 


30  PHTSIOGR-U'HIC  PKOCESSES. 

the  subject  of  diastropliism  for  the  purpose  uuder  eousideratiou ; 
namely,  to  exphiiu  the  origin  and  characteristics  of  the  surface 
featiu'es  on  the  earth. 

Gradation. — This  process  is  accomplislied  through  the  ageuey 
of  water.  First,  the  rocks  must  be  disintegrated;  second,  the 
rocks  must  be  transported ;  and,  third,  tlie  rocks  must  be  depos- 
ited. Thus  we  have  di.sititcf/rutioii,  iraiispoiiuti<»i^  and  deposi- 
tion. Rocks  are  disintegi-ated  by  chemical  action,  with  expansion 
and  contraction  by  changes  of  temperatm-e.  Rocks  are  disin- 
tegrated mechanically  chiefly  by  the  abrasion  of  streams  and 
glaciers.  Then  rocks  are  undermined  and  broken  down  by 
gravity  in  the  banks  of  streams,  and  in  cliffs  that  are  formed  in 
various  ways. 

The  material  transported  l)y  water  must  be  loaded,  and  it  is 
loaded  by  being  driven  by  rains  and  streams  from  higher  to 
lower  position  and  by  the  undermining  of  banks.  The  load  is 
heavier  than  the  water,  and  hence  it  sinks.  The  finer  the  mate- 
rial, the  longer  and  farther  it  will  be  carried  by  the  water,  while 
the  very  coarse  material  sinks  at  once.  The  swifter  the  current 
of  the  stream,  the  farther  the  load  wiU  be  carried.  But  this  is  in 
part  counteracted  by  another  condition  that  springs  from  the 
increase  of  the  velocity  of  the  current.  As  the  velocity  is  in- 
creased, the  depth  of  the  water  is  diminished,  and  the  load  has  a 
less  distance  to  fall  in  reaching  the  bottom.  In  streams  much 
material  is  diiven  along  at  the  bottom  as  it  is  rolled  over  by  the 
force  of  the  cm-rent.  As  a  stream  flows,  the  material  carried 
is  thi"own  down  from  time  to  time,  the  more  as  floods  subside, 
and  is  reloaded  from  time  tt)  time,  the  more  as  floods  arise, 
until  as  fine  sediment  it  is  carried  into  the  still  water  of  some 
lake,  or  into  the  sea,  where  it  is  assorted  and  arranged  by  waves 
and  currents,  and  is  mixed  with  the  sands  and  gravels  formed  on 
the  surf,  and  finally  consolidated  into  hard  rocks. 

The  rain  and  the  snow  are  spread  over  the  surface,  and  wash 
it  all ;  but  the  nils  that  come  from  snow  and  rain  run  in  little 
channels,  and  these  rill  channels  converge  into  brook  channels, 
and  brook  channels  into  creek  channels,  and  creek  channels  into 
river  channels.  We  have  therefore  two  ways  liy  which  the  Inud 
is  degraded  by  water,  which  should  ]>e  discriminated :  the  wash 
of  rain  and  snow  we  vnll  call  erosion,  and  the  cutting  of  channels 
by  streams  we  will  call  eorrasion.  No  perfect  separation  can  be 
made  between  these  two  processes;  l)ut  yet  eorrasion  must  be 


-Alarlilc  Ciiiiyoii  foi'i I  l,y  <],,■  ('nii:i«i(ni  of  i  lie  Coliirado  kivfi-. 


32  PHYSIOGRAPHIC  PROCESSES. 

discriminated  from  erosion,  for  by  corrasiou  deep  channels  are 
carved,  and  some  of  the  most  sublime  scenery  in  the  world  is 
dependent  upon  it,  for  the  great  cauycnis  are  carved  by  cori-asion. 

The  material  transported  by  streams  of  ice  is  loaded  in  two 
ways :  it  falls  from  overhanging  cliffs  to  the  surface  of  the  ice, 
and  it  is  plucked  by  the  ice  from  the  bottom  of  the  channel.  As 
the  ice  is  divided  by  cracks  and  again  reunited,  some  of  the  sur- 
face load  of  the  glacier  falls  to  the  bottom,  where  it  becomes 
imbedded,  along  with  the  i)lucked  fragments,  in  the  lower  layers 
of  the  ice.  Exceptionally,  and  in  ways  that  are  not  understood, 
some  of  the  material  escapes  from  the  lower  surface  of  the  ice, 
and  forms  local  deposits  over  which  the  ice  slides;  but  in  the  main 
all  the  glacier's  load  is  carried  forward  to  the  limit  of  its  motion, 
where  the  ice  melts,  and  the  load  is  dropped  in  an  irregular  heap 
called  a  moraine.  Streams  of  ice,  like  streams  of  water,  corrade 
their  channels,  iising  the  rock  fragments  l)edded  in  their  lower 
parts  as  cutting  tools,  and  the  rock  flour  thus  aliraded  becomes 
part  of  tlie  load  to  be  deposited  with  the  rest  in  the  moraine. 

It  will  be  seen  that  we  must  distinguish  three  grand  pi'ocesses 
by  which  the  features  of  tlie  surface  of  the  earth  are  i>roduced, 
—  nilcaiiisDi,  diastrophism,  and  yradatioii.  There  are  other  minor 
processes;  but  they  are  so  small  compai-ed  with  these,  that  for  our 
present  purpose  they  may  be  neglected.  All  we  have  hitherto 
said  has  had  this  result  in  view,  —  that  we  might  clearly  imder- 
staud  the  three  great  physiographic  processes. 

We  have  learned  of  three  great  moving  envelopes,  and  of 
how  they  are  in  motion;  and  in  studying  this  subject  we  have 
discovered  the  three  processes  by  which  the  features  of  the 
earth's  surface  are  molded  in  such  a  manner  that  we  have  seas, 
gulfs,  bays,  straits,  lakes,  rivers,  and  fountains,  and  that  we 
have  continents,  islands,  plains,  plateaus,  mountains,  hills,  and 
valleys.  How  all  of  these  features  are  produced,  and  many 
others  of  minor  importance,  must  be  the  theme  of  another 
pajier. 


PHYSIOGRAPHIC  FEATURES. 


By  J.  W.  PowTSLL. 


A  VOLCANO  in  actiou  is  a  scene  of  wondei-.  The  storm  of 
rock,  the  luminous  vapor,  and,  more  than  all,  the  exhibition  of 
stupendous  force,  condnne.  to  make  it  a  sublime  spectacle.  The 
method  by  which  a  volcano  is  constructed  was  explained  in  a  for- 
mer monograph  as  a  jiart  of  the  great  process  of  vulcaiilsm.  In  the 
same  monograph  the  manner  in  which  great  blocks  of  the  crust 
of  the  earth  are  upheaved,  tilted,  flexed,  and  folded,  was  sho\\^l, 
and  the  process  by  which  this  upheaval  is  carried  on  was  called 
(Uasfrophism.  Diastrophism  also  has  elements  of  sublimity ;  not 
to  untrained  sense,  but  only  to  instructed  reflection,  that  under- 
stands the  gi-and  energies  employed  and  the  mighty  works  done. 
Again,  it  was  explained  that  mountains  and  plains  are  carved  by  \ 
rains  and  streams,  leaving  behind  plateaus,  mountains,  hills,  and 
valleys ;  and  this  process  was  called  (iradatloit.  The  sublimity  of 
the  processes  of  gradation  is  grasj^ed  only  by  reflection  on  the 
energy  of  the  sun  in  lifting  the  waters  of  the  sea  into  the  air, 
and  driving  them  in  flocks  of  clouds  over  the  lan<l,  and  Inu'ling 
them  in  storms  to  beat  the  rocks  into  sands  and  bear  them  away 
to  the  bosom  of  the  ocean  whence  the  waters  were  lifted.  If  these 
three  processes  are  jiroperly  comprehended,  then  it  is  possible  to 
understand  the  origin  of  the  physical  filatures  of  the  surface  of 
the  earth,  such  as  continents  and  islands,  seas  and  lakes,  to- 
gether with  such  forms  as  plains,  plateaus,  moiintains,  valleys, 
hills,  and  many  other  interesting  features. 

The  ocean  covers  about  three  fourths  of  the  surface  of  the 
earth;  and  arms  of  the  sea  extend  into  the  land,  forming  gulfs 
and  bays.  Strictly  speaking,  all  lands  are  islands.  The  two 
Americas  together  constitute  an  island,  and  the  entire  island 
is  sometimes  called  the  Western  Continent ;  and  sometimes  North 
America  and  South  America  are  each  called  a  continent.    Eu- 


(Copyright,  1895,  by  American  Book  Company.) 
33 


34  PHYSIOGRAPHIC  FEATUEES. 

rope,  Asia,  and  Africa  together  constitute  another  gi-eat  island, 
the  largest  of  the  earth.  This  island  is  sometimes  called  the 
Eastern  Continent ;  and  sometimes  Europe,  Asia,  and  Africa  are 
severally  called  continents.  Australia  is  another  great  island, 
and  is  sometimes  called  a  continent.  In  addition  to  these  gi'eat 
continental  islands,  there  are  many  smaller  islands.  All  of  these 
islands,  continental  and  minute,  —  that  is,  all  of  the  land  sur- 
faces of  the  earth, —  have  been  sea  bottom  at  some  time  or  other, 
and  the  waves  of  the  ocean  have  rolled  over  them  all ;  they  have 
all  been  brought  above  the  level  of  the  sea,  and  have  all  been 
fashioned  into  their  present  forms  by  the  joint  action  of  %Tilcan- 
ism,  diastrophism,  and  gi'adatioii.  The  ocean  has  its  shores 
fretted  with  many  salients,  as  gulfs  and  bays,  all  due  to  the  three 
gi"eat  processes.  How  the  forms  of  land  and  water  are  produced 
is  the  story  now  to  be  told. 

PLAINS   .\ND   PLATEArS. 

Plains. — Whenever  in  any  region  the  process  of  slow  up- 
heaval comes  to  an  end,  and  such  district  is  still  subject  to  degra- 
dation by  rains  and  streams,  the  process  of  reduction  goes  on 
until  the  surface  is  brought  down  to  the  level  of  the  sea  or  lake 
into  which  its  waters  discharge.  At  the  same  time  the  land  may 
increase  in  area  by  the  deposit  of  sediments  which  have  been 
carried  away  from  its  surface  and  added  to  its  margin  :  in  this 
manner  the  low  plain  is  enlarged.  A  phihi,  therefore,  may  be 
due  in  part  to  degi-adation  and  in  part  to  sedimentation.  By 
one  or  both  methods  all  plains  are  formed.  The  huse-levd  of  a 
plain  is  the  level  of  the  sui'face  of  the  sea,  lake,  or  stream  into 
which  the  waters  of  the  plain  are  discharged. 

Sea  I'lains. — The  sea-level  plain  is  permanent  in  the  absence 
of  diastrophism,  for  it  cannot  be  degraded  below  the  action  of 
waves.  It  will  be  understood  that  the  land  plain  which  is  brought 
down  to  the  level  of  the  sea  has  its  margin  on  the  seashore,  and 
that  it  extends  l)ack  from  the  shore  a  distance  which  may  be 
miles  or  hundreds  of  miles.  As  it  stretches  back,  its  surface  rises 
slightly.  The  whole  plain  is  not  brought  down  absolutely  to  the 
level  of  the  sea,  but  only  nearly  to  that  level,  so  that  the  water 
runs  off  by  slow,  deep,  meandering  streams.  The  wash  of  the 
rain  over  the  surface  is  comparatively  little,  and  the  slow  streams 
are  usually  clear,  or,  when  turbid,  are  stained  with  Itlack  soil, 


PLAINS.  35 

Ijut  they  do  not  carry  great  quantities  of  mud.  Such  is  the 
typical  plain  as  it  borders  the  sea.  Low  lands  with  sm-faces 
more  inclined,  and  with  more  swiftly  running  streams,  are  still 
called  plains,  though  they  are  not  fully  brought  down  to  base- 
level;  sometimes  they  are  called  2)cn('2)l(iiii.'i  (almost  jJains). 

Lake  Plains. — Other  plains  may  be  formed  with  their  base- 
level  depending  upon  the  levels  of  lakes.  Such  plains  are  in 
the  interior  of  the  land,  and  may  be  high  above  the  sea.  The 
base-level  of  a  lake  is  not  permanent,  like  that  of  the  sea,  but  is 
changeable.  Every  fresh-water  lake  has  an  outlet  or  stream  by 
which  it  overflows  the  lake  barrier.  This  stream  may  cut  the 
barrier  down ;  that  is,  it  may  corrade  its  channel  deeper.  The 
deepening  of  the  channel  commences  Ijelow,  away  from  the  lake, 
and  progresses  back  upstream  until  the  lake  is  readied.  Then 
the  waters  of  the  lake  rush  througli  the  newly  opened  cliannel, 
and  the  lake  is  drained  in  whole  or  in  part.  The  plain  depend- 
ing upon  such  a  lake  will  tln;s  have  its  base-level  changed. 
If  a  lake  is  thus  partially  di'ained,  the  new  dry  land  stretches 
back  to  the  old  shore  line,  where  bluffs  have  been  formed  by  the 
waves.  This  old  shore  line  with  its  bluffs  is  a  conspicuous  ter- 
race step  to  the  older  and  higher  plain.  A  lake  may  change  its 
level  in  such  manner  from  time  to  time,  and  a  series  of  old  shore 
lines  may  be  left,  so  that  a  series  of  plains  will  appear  separated 
by  low  t'errace  steps.  Terraced  plains  are  often  formed  about 
lakes  in  this  manner. 

Stream  Plains. — A  river  maybe  hunch'eds  of  miles  in  length. 
As  it  flows  along,  it  passes  through  rocks  of  varying  degi'ees  of 
hardness.  Where  the  rocks  are  firm  and  stable,  corrasion  of  the 
stream  is  slow;  where  the  rocks  are  soft,  corrasion  is  more  rapid. 
In  this  manner  the  river  is  divided  into  lengths,  or  reaches.  Along 
its  course  where  the  rocks  are  hard,  the  stream  is  narrow  and 
swift,  with  rapids  and  faUs;  where  the  rocks  are  soft,  it  is  wide 
and  quiet.  So  the  river  is  often  a  stairway  from  an  ujjper  to  a 
lower  region.  The  slow  reach  is  a  hase-lerel,  like  that  of  a  lake, 
below  which  the  l)anks  and  hills  on  either  side  cannot  bo  do- 
graded  ;  and  local  plains  are  thus  formed,  which  rise  gently  back 
from  the  river.     These  we  will  call  stream  plains. 

Sometimes  another  process  provides  SAvift  reaches  to  rivers: 
diastrophism  is  the  agent.  There  may  be  a  slow  upheaval  of 
the  land  athwart  the  com-se  of  the  stream.  As  the  land  rises, 
the  river  cuts  its  channel,  so  that  it  still  flows  on  :  for  the  faster 


36 


PHYSIOGKAPHIC  FEATURES. 


the  land  rises,  the  swifter  is  the  current ;   and  the  swifter  the 

ciUTent,  the  more  rapidly  the  rocks  are  cut  away.     So  the  river 

jcorrades  its  way  through  obstructing  rocks  as  they  rise  bydias- 


Urceii  liii\('r  ciillin;^^  its  *  imuiu'l  tlirougU  llu'  i  iiiiali  MimuiMiii^  .i>  iiii_\   il^^c 
athwart  its  Course. 

trophism.  Such  an  upheaval  of  rock  across  the  current  of  a 
stream  may  last  for  a  long  time,  and  the  river  may  be  held  to  a 
base-level  for  all  that  time,  and  extensive  plains  may  be  carved. 


PLAINS.  37 

The  preservation  of  a  local  base-level  of  a  river  iu  this  manner 
is  common.  In  the  history  of  a  plain  thus  formed,  terracing  may 
occur  like  that  made  by  the  lowering  of  lakes.  This  is  accom- 
plished by  the  cutting  away  of  the  swift  reaches,  which  changes 
the  base-level  of  the  slow  reach  above.  So  the  local  plains  are 
sometimes  terraced. 

Flood  Phthis. — In  the  history  of  a  river  a  slow  reach  is  soon 
formed  immediately  above  its  mouth,  where  it  enters  a  lake  or 
the  sea,  and  this  slow  reach  is  gradually  extended  upstream 
until  it  is  tens  or  hundreds  of  miles  long.  In  the  jjrocoss  of  ex- 
tending the  slow  reach  up-river,  the  swift  reaches  iu  the  hard 
rock  are  cut  out,  so  that  the  river  has  but  a  low  declivity.  The 
stream  cariies  sediment,  which  it  deposits  just  outside  its  mouth, 
and  thus  a  delta  is  foi-med.  So  the  slow  reach  at  tlie  mouth  of 
the  river  is  lengthened  downstream  by  the  growth  of  the  delta, 
and' upstream  by  the  coi'rasion  of  the  channel  down  to  the  base- 
level. 

River  channels  are  corraded  by  their  own  waters,  and  the 
streams  use  the  sediments  which  they  contain  as  the  instnnnent 
of  corrasion.  As  a  river  cuts  its  channel  down  toward  the  base- 
level,  it  has  less  and  less  vertical  cutting  to  perform,  and  then 
its  energies  are  turned  against  its  banks.  The  way  in  which 
this  is  done  is  of  gi'eat  interest.  As  the  declivity  of  the  stream 
is  less,  the  water  of  the  stream  is  retarded  in  its  flow,  and  the 
sediment  carried  in  the  water  is  more  rapidly  deposited  Ijccause 
the  waters  are  more  quiet;  that  is,  the  distance  to  which  the 
load  is  carried  is  shorter.  The  swift  stream  carries  its  load 
much  farther  than  the  slow  stream. 

A  curved  stream  has  slow  reaches  and  swift  reaches.  "WHiere 
the  water  is  slow,  bars  are  formed,  for  there  the  load  is  thrown 
down ;  where  the  water  is  swift,  the  channel  is  cut,  for  there  the 
load  is  an  instrument  of  corrasion.  Against  the  outside  bank  of 
curves  the  river  flows  with  a  swift  current,  and  cuts.  Along  the 
inside  bank  the  current  is  slow,  and  deposits  are  formed.  A 
deposit  formed  on  the  inside  bank  throws  the  water  still  more 
against  the  outside  bank.  Thus,  while  one  bank  is  built,  the 
other  bank  is  cut ;  for  on  one  side  the  current  of  the  stream  is 
swift,  and  on  the  other  side  the  cui-rent  is  slow.  These  jjlaces 
of  deposition  and  lateral  corrasion  are  modified  in  many  ways 
that  need  not  be  considered  here. 

As  a  river  ceases  to  corrade  vertically,  it  gradually  begins  to 


STATE  NOfiMALSCHOOL 

1 ,0&  AKiifiX-iiiS. -:- OAC* 


38 


PHYSIOGRAPHIC   FEATURES. 


Mississippi  Kiver.  near  Greenville, 
Miss. 


coiTade  horizontally  or  laterally. 
Thus  vertical  corrasion  is  turned 
iiito  lateral  corrasiou.  The  banks 
are  cut  in  one  plaoe,  and  the  load  is 
deposited  iu  bars  in  another.  So 
banks  are  built  and  banks  are  car- 
ried away ;  and  when  the  stream 
has  practically  i-eached  its  base- 
level  iu  the  sea  or  lake  into  which 
it  discharges,  aU  its  corrasiou  is 
lateral,  antl  the  cut  at  every  out- 
side bank  adds  to  the  instrument 
of  corrasiou,while  the  bar  of  every 
inside  bank  adds  to  the  force  of 
thewateragainst  the  opposite  side 
and  below,  so  that  the  currAit  is 
thrown  against  the  banks  more 
aud  more,  and  loaded  more  and 
more,  until  the  rate  of  lateral  cor- 
rasiou is  much  greater  than  was 
the  rate  of  vertical  corrasion. 

Kivers  subject  to  lateral  coitet 
siou  iu  this  manner  ever  change 
theu'  courses,  ploA\"iug  to  the  right 
and  plowing  to  tlie  left,  sendiug 
their  cm'ves  far  back  toward  the 
hills  mitil  curve  meets  curve  in  its 
outer  limit,  aud  a  cnt-off  is  pro- 
duced. A  gi-eat  river  iu  a  flood 
plain  squirms  like  a  great  serx>eut 
on  the  desert.  "With  every  fold 
iu  its  long  form  it  cuts  away  new 
land  on  oue  side,  aud  builds  up 
new  land  on  the  other.  So  such 
rivers  sway  back  and  forth  across 
their  valleys,  and  dig  away  the 
laud  on  both  sides  down  to  the 
bottom  of  their  channels,  always 
to  build  it  up  again.  A  wide  val- 
ley is  carved  by  the  river  to  the 
level  of  its  bottom,  aud  built  up 


PLATEAUS.  39 

again  iu  a  plain  to  the  level  of  its  high  water;  and  this  built 
plain  in  an  excavated  valley  is  known  as  a.  flood  plain.  Such  a 
flood  plain  may  be  formed  along  any  quiet  reach  of  the  river  from 
its  source  to  the  sea. 

So  we  have  sea  plains,  lake  plains,  stream  plains,  and  flood 
plains. 

Plateaus.  Diastrophlc  I'lateaus. —  When  iu  a  great  district 
of  country  the  process  of  upheaval  has  fairly  set  in,  it  may 
continue  for  an  indefinite  time;  and  the  land-formed  or  sea- 
formed  plain  may  rise  higher  and  higher  as  the  centuries  roll  by, 
until  it  is  lifted  hundreds  or  even  thousands  of  feet  above  the 
level  of  the  sea.  As  it  is  carried  u[)  iu  this  manner,  rains  fall 
upon  it  aud  dig  it  down,  and  the  streams  carry  the  matei'ial  away. 
The  principal  rivers  cut  their  channels  deeper  and  deeper,  the 
lateral  rivers  cut  their  channels  deeper  and  deeper,  the  creeks  cut 
their  channels  deeper  and  deeper,  and  the  rills  that  run  only  when 
the  rains  fall  cut  their  chainiels  deeper  and  deeper,  so  that  the 
rising  plain  is  divided  by  a  multitude  of  large  and  small  streams ; 
but  the  summits  between  the  streams  remain  for  a  much  longer 
time,  and  preserve,  in  a  rough  way,  a  general  level.  The  site  of 
the  old  plain,  marked  by  the  hilltops,  will  long  be  visible  to  the 
skilled  eye  of  a  geographer.  Wlien  a  plain  has  thus  been  uplifted 
and  carved  with  stream  channels  while  the  hilltops  yet  renuiin  to 
mark  the  surface  of  the  old  plain,  it  is  called  a  j)Iaf('ai(.  Tluis 
plains  are  due  to  gradation  ;  plateaus,  to  diastrophism  and  grada-  i 
tion.  It  is  manifest  that  tlie  plain  thus  gi-adiially  merges  into  \ 
the  plateau  by  process  of  upheaval  and  gradation.  For  tliis  reason 
it  is  not  practicable  to  clearly  discriminate  plateaus  from  plains, 
and  in  the  common  practice  of  applying  names  some  confusion 
arises.  The  same  region  of  country  will  sometimes  be  called  a 
plain,  and  sometimes  a  plateau;  for  a  plateau  is  biit  an  elevated 
plain,  and  the  degree  of  elevation  and  gradation  to  which  it  iiuist 
submit  ere  its  name  is  changed  cannot  always  be  determined 
with  exactness. 

A  great  plain,  as  it  is  lifted  up,  maj''  be  broken  into  parts  by 
another  agency;  that  is,  hy  fractKring  and  fault  in  ff ;  and  the 
blocks  into  which  it  is  thus  divided  may  be  variously  lifted  and 
tilted.  In  such  cases  tlu^  edgi^  of  the  i)lateau  may  still  be  defined 
as  the  escarpment  of  a  gi'eat  fault.  Such  displaced  blocks  are 
quite  common  in  some  parts  of  the  United  States.  All  plateaus 
that  are  formed  by  the  upheaval  of  plains,  and  ci;t  into  parts  by 


40  PHYSIOGKAPHIC  FEATUKES. 

rivers,  or  broken  into  parts  by  faults,  or  divided  into  parts  by 
flexiu'es,  Ave  will  call  (riastropJiic  -plateaus. 

Vulcanic  PUdeaiis. —  In  the  study  of  vulcanism  we  learned, 
how  volcanoes  were  formed,  and  bow  coulees  of  lava  were  poured* 
out  on  the  surface  of  the  earth,  and  how  strata  of  dust  and  ashes  j 
were  spread  over  the  land.  Now,  di;st  and  ashes  poured  o\it  in 
this  manner,  together  with  coulees  of  lava  piled  up  one  upon 
another  over  a  gi'eat  region  of  countiy,  may  produce  a  plateau. 
So  we  have  ritlcfDiic  plateaus. 

A  plateau  is  only  a  lifted  and  rather  irregular  plain,  and  a 
plain  is  a  more  regular  and  less  lifted  plateau.  Should  we  call 
them  all  plains,  then  we  would  have  plains  of  gradation  or  time 
plains,  (Viastrophic  plains  {diastrophic  plateaus),  and  vulcanic 
plains  {vulcanic  plateaus). 

MOUNTAIXS. 

Vulcanic  Mountains.   Tush'ar  Mountains.  — Vulcanic  plateaus 
are  common  as  great  elevations  of  laud  composed  of  coulees, 
beds  of  cinders,  knd  accumulations  of  ashes.     Sometimes  small 
cinder  cones  are  found  as  weU-developed  forms,  and  old  cinder 
cones  appear  more  or  less  degraded.     As  the  lavas  are  poured  out  ' 
and  piled  up,  streams  cai"ve  canyons,  gulches,  and  valleys,  which 
from  time  to  time  may  be  again  filled  with  •vulcanic  material  from  '- 
below.    Finally  the  "siilcanic  action  ceases,  and  such  plateaus  are  i 
carved  into  mountains.    In  the  United  States  the  greater  number 
of  vulcanic  mouiltains  are  of  this  character,  composed  wholly  of  j 
vulcanic  rocks.    More  or  less  modified  by  diastrophism,  they 
are  called  tushar  mountains. 

Volcanoes. — "We  have  akeady  seen  how  mountains  are  poui-ed 
out  from  the  interior  of  the  earth  through  volcanic  vents.  Such 
extravasation  is  always  intermittent.  Sheets  of  lava  are  poured 
out,  and  flow  down  the  sides  of  the  mountain,  and  build  it  higher. 
Then  the  action  ceases  for  years  or  centuries,  to  be  renewed  from 
time  to  time.  The  years  of  rest  are  many  more  than  the  years 
of  activity,  and  in  tliem  great  changes  occur.  The  beds  of  lava 
are  covered  with  vegetation;  rains  and  snows  fall  upon  them; 
and  streams  wear  them  away,  cutting  canyons  and  excavating 
valleys,  until  at  last  new  floods  of  rock  come  to  destroy  old  for- 
ests, bury  old  canyons,  and  fill  old  valleys.  Volcanoes  are  in  this 
manner  built  from  materials  lirought  from  below  as  molten  lava 
or  as  cinders  and  dust ;  but  the  process  is  slow  and  intermittent. 


MOUNTAINS.  41 

and  ouly  portions  of  each  vulcanic  flood  remain  in  the  stmcture 
of  the  mountain.  When  the  fires  at  last  cease  and  the  volcanoes 
are  dead,  rains  and  rivei's  tear  thoni  down  until  the  i)eaks  are 
all  carried  away,  and  only  fragments  are  l(>ft  as  columns  of  \\i\- 
canic  rock  formed  in  the  ancient  chimneys. 

LaccoVific  Mountains.  —  There  is  another  class  of  \"nlcanic 
mountains  of  great  interest,  though  not  so  common  as  the  vol- 
canoes already  described.  Lava  coming  from  the  interior  of  the 
earth  through  the  crust  or  i-ock  (envelope  does  not  always  reach 
the  surface:  it  may  rise  through  the  lower  beds,  and  come  with- 
in a  few  hundred  feet  of  the  surface,  and  force  its  way  laterally 
between  the  sedimentary  beds,  because  the  lavas  have  a  greater 
specific  gravity  than  the  limestones,  shales,  and  sandstones  of 
sedimentary  origin.  As  the  lavas  are  forced  laterally  in  this 
manner  between  the  sedimentary  rocks,  slowly  the  upper  beds 
are  lifted,  and  great  dome-shaped  mountains  are  fomied  with 
cores  of  lava  or  igneous  rock,  and  strata  of  sedimentary  rock 
arched  over  them.  The  cores  of  lava  are  called  htrcolitcs,  and 
the  mountains  thus  formed  laccoUtic  mountains.  Rains  fall  on 
these  laccolitic  mountains  as  upon  all  othei's;  and  the  streams 
formed  thereon  carve  gorges,  and  sometimes  cut  through  the 
sedimentary  rocks,  and  reveal  the  laccolites  within. 

Tahle  Mountains. — A  great  sedimentary  iilatoau,  while  un- 
dergoing gradation  by  rains  and  rivers,  may  be  rent  by  fissures, 
and  lavas  poured  out.  The  coulees  spread  over  the  surface  of 
sedimentary  rocks  in  this  manner  prevent  for  a  long  time  the 
underlying  sedimentary  rocks  from  degradation,  foi-  the  lavas 
are  much  harder.  As  the  adjacent  country  is  washetl  down,  the 
region  protected  by  coulees  remains  as  a  plateau,  not  very  large, 
and  is  called  a  tahle  mountain. 

liiihrirafed  ^fountains.  —  Such  a  lava-cut  plateau  or  table 
mountain  may  become  the  core  of  a  greater  mountain.  Around 
the  flanks  of  such  a  low  mountain  new  fissures  open,  through 
which  lavas  are  poured,  and  coulees  are  thus  spread  over  the 
flanks  of  the  old  table  mountain.  Still  degradation  progresses, 
and  the  valleys  about  the  mountain  are  excavated  deeper ;  and 
as  this  process  goes  on,  other  coiilees  are  poured  out  at  still 
lower  elevations.  In  such  manner  the  core  of  sedimentary  rocks 
is  sheathed  with  coulees,  and  a  gi'eat  mountain  is  formed  with 
its  central  body  of  sedimentary  rocks,  and  its  covering  of  vul- 
canic rocks. 


42  PHYSIOGRAPHIC   FEATURES. 

Special  forms  of  vulcanio  moiiutaius  have  been  described  as 
volcanoes,  laccoUtic  nioiiiitaius,  tahle  luoimtaius,  aud  imbricated 
mountains. 

It  must  be  clearly  understood  that  vulcanism  and  gradation 
cooperate  in  producing  ^iilcanic  mountains.  The  materials  are 
thrown  out  from  the  interior  of  the  earth,  and  piled  up  in  irreg- 
ular masses,  and  then  fashioned  by  the  sculptm-e  of  waters. 

DiASTROPHic  MorxTAixs. —  AVe  have  already  seen  how  pla- 
teaus are  fonned  by  diastrophism.  Beds  of  rock  are  uplifted, 
and  tilted  more  or  less ;  and  as  great  regions  are  forced  up  in  this 
manner,  the  raius  fall  upon  them,  and  gi-ade  them  down.  Ex- 
tensive areas  that  were  plains  are  lifted,  and  are  cut  into  plateaus 
by  streams,  or  broken  into  plateaus  by  great  faults,  or  di\ided  by 
great  flexures.  Then  these  plateaus  are  still  further  carved  by 
clouds,  whose  greater  tools  are  rivers  and  glaciers,  and  whose 
finishing  instruments  are  brooks  and  rills.  With  them  the 
diastrophic  plateaus  are  fashioned  into  mountains,  with  can- 
yons, gorges,  and  valleys  intervening. 

We  have  already  learned  of  sedimentary  rocks  and  metamor- 
phic  rocks.  These  metamorphic  rocks  were  formerly  deep-seated. 
They  were  at  one  time  sedimentary  and  igneous  rocks,  h'ing  in 
strata,  gi-eat  beds,  and  masses,  and  were  afterward  covered  by 
sedimentary  rocks;  that  is,  their  stratigraphic  place  is  below 
the  imaltered  sedimentary  rocks,  l)ut  in  the  upheaval  of  great 
plateaus  these  deeply  seated  rocks  have  come  to  the  surface,  and 
often  constitute  the  rocks  found  at  the  summit  of  high  moun- 
tains. Mountains  of  this  class  often  have  a  core  of  metamorphic 
rocks,  with  sedimentary  rocks  inclined  on  the  flanks.  Some- 
times the  sedimentary  rocks  ai"e  carried  away,  and  it  may  be 
that  such  plateaus  were  formed  in  metamorphic  rocks  where 
sediments  have  not  subsequently  been  deposited  over  them, 
though  this  is  not  known  with  certainty ;  yet  we  do  know  that 
there  are  mountains  which  seem  to  be  composed  of  only  meta- 
morphic rocks,  though  it  is  probable  that  they  are  only  frag- 
ments of  plateaus  whose  overhing  sedimentary  beds  have  been 
carried  away.  Many  of  the  mountain  ranges  of  the  world  have 
metamorphic  cores  ^vith  sedimentary  beds  on  their  flanks.  Many 
mountain  ranges  are  composed  exclusively  of  sedimentary  beds, 
and  other  mountains  of  metamorphic  rocks,  while  all  vulcanic 
mountains  have  another  structure. 

Thus  in  diastrophic  mountains  three  varieties  are  to  be  noted, 


MOUNTAINS.  43 

—  metamorphic  moimtains,  mouutaius  with  metamorphic  cores, 
and  sedimentarij  mouutaius.  Agaiu,  we  must  note  that  dias- 
ti'ophisui  is  the  agency  by  which  great  lilocks  have  been  up- 
lifted, and  that  the  minor  mov^ntain  forms  are  due  to  gi'adation. 

Grouping  of  Mountains. — Volcanoes  are  sometimes  isolated, 
but  they  are  more  ofteu  grouped  in  assemblages  of  gi'eat  and 
small  peaks. 

Diastrophic  mountains  are  commonly  arranged  in  lines,  and 
are  then  called  ranges.  Thv;s  a  number  of  mountains  may  be 
carved  out  of  a  huge  wrinkle  which  would  have  formed  a  great 
round-backed  plateau,  had  it  not  been  for  the  water.  Such  great 
wrinkles  are  sometimes  jiarallel  with  one  another,  and  thus  ranges 
are  grouped  into  systems  of  parallel  lines.  The  ranges  them- 
selves may  be  complicated,  and  associated  with  vulcanic  moun- 
tains. The  wrinkles  of  which  ranges  are  formed  may  not  stand 
abreast  of  one  another,  but  one  may  overlap)  another;  that  is, 
extend  beyond  it  in  one  direction,  while  the  first  nuiy  extend  be- 
yond the  second  in  the  other  direction.  Mountain  ranges  Ij'ing 
in  this  shape  are  said  to  be  in  echelon.  Parallel  ranges  and  eche- 
lon ranges  are  sometimes  complicated  with  vulcanic  mountains, 
and  may  extend  over  great  geograpliic  areas  as  extensive  moun- 
tain systems.  Between  the  ranges  great  valleys  lie,  and  between 
the  mountains  of  every  range  smaller  valleys  are  formed. 

And  yet  there  is  another  way  in  which  mountains  are  grouped. 
A  great  district  of  covmtry  may  be  upheaved  as  a  block  hundreds 
of  miles  long  and  scores  of  miles  wide.  One  edge  of  the  block 
may  be  much  higher  than  the  other;  then  the  streams  that 
gather  on  the  block  roll  from  the  upturned  mai-gin  down  with 
the  dij)  of  the  beds  into  the  great  valley  or  plain  below,  and  carve 
gulches  and  valleys  across  the  block.  Such  ranges  are  moi-e 
or  less  transverse  to  the  longitudinal  direction  of  tlie  block. 
Thus  great  s})urs  are  formed  extending  from  the  crest  to  the 
great  valley.  Such  a  system  of  mountains  may  be  composed  of 
more  or  less  parallel  ridges  that  stand  abreast  of  one  another  in 
a  long  line.  These  ridges  usually  have  culminating  peaks  on  the 
side  where  the  block  was  lifted  to  the  greatest  altitude.  The 
Sierra  Nevada  is  a  system  of  mountains  of  this  character.  Others 
on  a  scale  less  grand  are  found  in  various  parts  of  the  United 
States. 

Now,  it  must  be  clearly  undei-stood  that  in  explaining  the 
character  of  various  mountains  it  is  not  possible  to  make  a 


44  PHYSIOGRAPHIC  FEATVKES. 

classification  which  can  always  be  clearly  demarcated.  It  has 
been  shown  that  plateaus  are  sometimes  partly  Aiilcanic  and 
partly  diastrophio.  As  regions  are  lifted,  vulcanic  forces  are 
arc)used,  so  that  diastrophic  mountains  are  often  complicated 
with  vulcanic  mountains.  A  fissm-e  is  gi-adually  produced,  upon 
one  side  of  which  a  block  is  uplifted  to  be  carved  into  moun- 
tains. At  the  same  time,  lavas  are  poured  through  the  fissure, 
and  mountains  are  built.  Along  such  fissui'e  a  complex  range 
is  formed,  one  side  of  which  is  of  diastrophic  origin,  the  other 
side  of  vulcanic  origin ;  and  the  peaks  of  such  a  range  may  be  in 
part  \'ulcauic  and  in  part  diastrophic.  Yet  in  other  but  minor 
ways  the  two  gi'eat  classes  of  mountains  are  complicated  with 
each  other,  but  it  will  be  clear  that  mountains  express  the  differ- 
ence between  elevating  processes  and  grading  processes. 

VALLEYS. 

Plateaus  and  mountains  afford  the  most  picturesque  sceneiy 
fur  the  delight  of  man,  but  on  plains  and  in  valleys  he  chiefly 
makes  his  home.  As  plains  and  plateaus  are  classified  by  the 
great  physiogi'aphic  processes,  and  as  moimtains  are  classified 
in  like  manner,  so  valleys  fall  into  three  great  groups,  though 
this  classification  must  not  be  understood  as  implpng  that  the 
classes  can  always  be  clearly  distinguished. 

VrLCAXic  V-O^LEYS. — AVheu  groups  of  volcanoes  are  con- 
structed of  coulees,  cinders,  and  ashes,  valleys  are  formed  be- 
tween the  mountains.  The  rains  and  streams  modify  these 
valleys,  enlarging  them,  and  excavating  stream  channels;  but 
the  origin  of  such  valleys  is  to  be  found  in  Aiilcanism. 

Diastrophic  V.vlleys. — "When  lands  are  uplifted  in  broken 
blocks  or  gi-eat  folds,  the  lowlands  constitute  valleys.  Such 
diastrophic  valleys  are  also  modified  by  gradation. 

^lany  valleys  are  inclosed  in  part  by  \Tilcauic  mountains, 
and  in  part  by  diastrophic  mountains. 

Valleys  of  CtEadatiox. — Upheaved  plains  are  divided  into 
plateaus  by  the  corrasion  of  streams,  and  the  plateaus  also  are 
trenched.  As  time  passes  on  through  geologic  ages,  stream 
channels  ai"e  widened  into  valleys,  and  a  ramifying  system  of 
stream  channels  into  gi-eat  valleys.  Systems  of  streams  uniting 
with  systems  of  streams  carve  still  greater  valleys.  Most  of  the 
valleys  of  the  world  are  produced  in  this  manner. 


HILLS.  45 

Thus  we  have  foiind  vulcanic  valleys,  diastrophk  valleys,  and 
fjradatioH  valleys.  Compound  valleys  produced  by  all  these  agen- 
cies are  found. 

HILLS. 

Over  all  the  land  the  hills  are  scattered.  Hills  rise  from 
plains,  hills  are  embossed  on  plateaus,  hills  are  grouped  about 
mountains,  and  hills  are  scattered  through  the  valleys.  No 
definite  distinction  can  be  made  between  hills  and  mountains. 
The  smaller  forms  are  usually  called  hills;  the  larger,  mountains; 
but  the  usage  is  not  consistent.  Forms  that  are  called  moun- 
tains ill  one  region  would  be  called  hills  in  another,  and  rice 
versa.  Where  there  are  great  mountains  in  sight,  somewhat 
smaller  forms  are  often  called  hills ;  while  in  another  region  forms 
of  equal  magnitude  would  be  called  mountains. 

Vulcanic  Hills. — As  ^nilcanic  plateaus  are  carved  into  moun- 
tains, these  mountains  are  still  further  carved  into  hills,  and  we 
have  hills  of  gradation  composed  of  vulcanic  rocks.  Vulcanic 
hills  are  chiefly  of  this  chai'acter,  but  there  are  other  kinds  that 
require  mention. 

Cinder  Cones. — As  vulcanic  fires  go  out,  the  expiring  ener- 
gies often  Iniild  cinder  cones;  and  over  a  vulcanic  region  cone- 
shaped  hills  are  found,  often  much  woi'ii  down  ]>y  rains. 

Coulee  Hills. — When  molten  matter  is  poured  over  the  sur- 
face of  the  earth  in  coulees,  it  slowly  congeals,  and  slowly  moves 
in  great  sluggish  waves,  and  the  red-hot  rock  is  transformed  into 
cold  black  I'ock.  In  this  manner  waves  of  liquid  rock  are  frozen 
into  somber  hills  of  low  magnitude.  So  a  great  coulee  often 
presents  a  surface  of  hills  and  valleys  as  wrinkles  of  the  waves 
by  which  it  progresses. 

DiASTROPHic  Hills. — Uplifted  plains  form  plateaus,  and 
these  plateaus  are  carved  into  hills  and  mountains,  while  the 
mountains  themselves  are  at  last  dissected  into  hills.  Thus  we 
have  hills  in  diastrophie  blocks  carved  by  waters.  The  carving 
of  plateaus  and  mountains  into  hills  is  accomi)lislied  not  only 
by  running  water,  l)ut  also  by  glaciers. 

Diastrophie  hills  present  some  interesting  relations.  As  the 
edges  of  plateaus  are  carved,  the  summits  of  the  hills  do  not 
appear  above  the  general  level  of  the  plateau  itself.  Ridges  Ije- 
tween  valleys  carved  in  plateaus  may  be  sharp ;  and  as  they  are 
progressively  degraded,  the  more  narrow  portions  may  become 


46  PHYSIOGRAPHIC  FEATURES. 

gaps ;  and  as  these  gaps  are  still  further  degraded,  the  tops  of 
the  hills  are  lowered.  Thus  some  hills  may  have  theii-  summits 
at  the  level  of  the  plateau ;  other  hiUs,  below  it.  As  the  process 
goes  ou,  the  whole  plateau  may  be  cut  into  hills  of  irregular  alti- 
tudes. As  the  process  still  goes  on,  aud  the  valleys  ai'e  enlarged, 
the  hills  become  more  unequal  in  height,  and  fewer  in  number. 
In  the  same  manner  mountains  are  carved  into  very  irregular 
hills.  Thus  it  is  that  we  may  ascend  hills  in  going  from  lower  to 
higher  districts  of  country,  and  such  hills  wiU  not  have  declivities 
on  all  sides ;  while  in  older  regions  of  degi'adatiou,  where  the  pla- 
teau structure  is  wholly  or  in  part  lost,  the  hills  are  much  more 
irregular,  and  it  is  necessary  to  descend  from  ever}'  hill  in  order  to 
reach  and  climb  one  adjacent.  Hills  thus  isolated  are  sometimes 
called  hills  of  chctondomdutioii,  while  hills  which  extend  from 
the  summit  of  plateaus  to  plains  below  may  be  called  hiUs  of 
partial  denudation. 

GiiADATiox-iL  Hills. — Glaciers  build  hills  of  their  ovra.  They 
dig  down  mountains  and  plateaus,  and  carry  the  material  into 
the  valleys  and  over  the  plains,  and  deposit  it  in  hills.  The 
debris  carried  by  gla^-iers  forms  moraines.  "\Mien  glaciers  melt, 
this  material  is  left  in  irregular  heaps,  and  is  still  designated 
by  the  same  term.  Old  moraines  are  often  conspicuous.  They 
are  irregular,  aud  frequently  contain  hollows  which  hold  lakes. 
Terminal  moraines  usually  appear  as  ciu'ved  ridges  across  the 
course  of  the  ice  stream  by  which  they  were  formed.  Lateral 
moraines  form  sharp-crested  ridges,  aud  mark  the  mai'gin  of 
departed  glaciers.  Other  varieties  of  hills  due  to  the  same 
agency  are  named  with  reference  to  their  relation  to  the  ice 
which  formed  them. 

Besides  the  more  general  morainic  deposit  left  by  glaciers, 
there  are  interesting  and  frequently  very  conspicuous  topo- 
graphic forms  produced  by  special  agencies. 

Long  tunnels  are  sometimes  melted  out  beneath  ice  sheets, 
and  become  filled  by  streams  with  gi-avel  and  sand.  "WTien  the 
ice  melts,  these  deposits  are  left  as  long,  winding  ridges,  termed 
eskers. 

Al)oi;t  the  moraines  of  glaciers  where  streams  discharge  piles 
of  gravel  and  sand,  high  hills  are  formed  that  have  billowy  sur- 
faces, and  are  known  as  kames.  The  popular  name  for  a  group 
of  kames  in  certain  regions  is  "  kettle  hills,"  in  others  "  cup-and- 
saucer  hills ; "  the  cups  being  turned  upside  down  and  forming 


CLIFFS.  47 

rounded  knolls,  while  the  saucers  between  hold  water  and  form 
lakelets. 

As  an  ice  sheet  begins  to  melt,  streams  may  form  on  its  sm*- 
face,  and  cut  for  themselves  channels,  in  which  lodges  the  fine 
debris  imbedded  in  the  ice;  and  this  material  sometimes  remains 
in  long  ridges  of  loam,  called  2)nJ>a  in  Iowa,  where  they  abound. 

Tlie  debris  carried  out  by  moving  ice  masses  may  lodge, 
perhaps,  on  a  nucleus  of  rock,  and  the  ice  moving  over 
the  obstruction  gives  a  smooth  whale-back  form  to  the  hill. 
These  deposits  are  sometimes  termed  lo/tiriilar  hills,  or  dnnn- 
I'ms.  The  longer  axis  of  such  hills  lies  in  the  direction  of  the 
ice  movements. 

These  types  of  hills  formed  by  glacial  action  are  the  most  com- 
mon, and  are  characteristic  of  many  regions,  but  other  forms  are 
known;  and  in  }nany  instances  the  different  types  are  so  com- 
mingled that  they  are  not  easily  distinguished. 

Sand  Dunes. — And  yet  there  is  another  class  of  hills  inter- 
esting to  the  geogra])her,  formed  hy  the  drifting  of  the  sand  by 
prevailing  winds.  On  the  shores  of  the  sea  the  rocks  are  ground 
into  sands,  and  long,  fringing  sand  beaches  are  produced.  Then 
the  winds  carry  these  sands  away,  some  to  the  sea,  and  some  to  the 
land.  Such  land-drifting  sands  are  formed  into  hills,  which  are 
known  as  sand  dunes.  Lake  shores  and  river  banks  have  their 
sand  beaches,  and  deserts  often  present  great  stretches  of  naked 
sand,  all  of  which  are  drifted  into  dunes.  All  dunes  travel.  The 
sand  is  carried  from  the  windward  side  and  deposited  upon  the 
leeward  side,  and  so  the  hills  journey.  So  we  have  seaheach 
dunes,  lake-shore  dunes,  strcain-haiik  dunes,  and  desert  dunes. 


CLIFFS. 

Cliffs  of  Gkadation. —  Streams  Avith  great  declivity  rap- 
idly corrade  their  channels.  In  cutting  down  through  hard 
rocks,  the  banks  remain  as  cliffs.  As  the  process  of  corrasion 
goes  on,  and  the  channels  are  cut  deeper,  the  cliffs  extend  higher 
above  the  water.  Channels  inclosed  by  cliffs  in  this  manner 
are  usually  called  canj/ons,  the  walls  of  which  are  cliff's  of  beauty. 
But  the  cliffs  break  down  l)y  gravity.  The  waters  percolat- 
ing through  the  joints  of  the  rocks,  and  streaming  down  the 
mural  faces,  gradually  break  them  up;  and  they  fall,  and  are 
piled  up  below  in  a  talus  of  loose  rocks,  which  is  still  fnrtlun* 


48 


PHYSIOGRAPHIC  FEATURES. 


worn  away  by  rains,  and  carried  into  the  streams,  where  it  is 
transported  away.  lu  this  manner  the  canyons  are  gi-adually 
>videned,  and  the  cliffs  become  steep  banks,  and  the  channels 
are  then  usually  known  as  gulches ;  but  the  gulches  themselves 


('liffs  of  tlie  (.'anvon  tie  Tsivi.  Arizuiia. 


increase  in  width  as  the  process  of  degi-adation  goes  on,  until 
valleys  separate  the  distinct  banks,  which  are  themselves  carved 
into  hills.     Sometimes  the  banks  retreat  by  a  peculiar  process 


CLIFFS.  49 

knowu  as  sappmg.  Harder  and  more  coherent  beds  above  are 
underlaid  with  softer  and  more  friable  beds  below;  then  the 
rocks  below  are  carried  away  more  rapidlj^  than  those  above. 
Thus  the  retreating  walls  are  forever  undermined,  and  the  rocks 
break  off  above  by  the  force  of  gi-avity,  to  be  ground  more  or 
less  in  the  fall,  and  to  be  washed  away  with  the  talus  below. 
Thus  a  cliff  is  maintained  which  retreats  slowly  through  the  cen- 
turies of  degradation.  In  the  same  manner  the  valley  is  widened 
continuously  while  yet  waUed  with  cliffs. 

As  the  land  still  rises  by  diastrophism,  the  stream  still  cuts  by 
corrasion,  and  may  cut  through  harder  and  softer  rocks  in  alter- 
nating strata  or  beds.  In  the  upper  rocks  the  cliffs  are  carried 
far  back  from  the  stream,  and  another  line  of  cliffs  may  be  es- 
tablished under  the  same  conditions,  the  upper  part  being  com- 
posed of  hard  beds,  the  lower  of  soft  l^eds,  and  another  line  of 
cliffs  may  thus  follow  the  wake  of  the  fii'st.  The  traveler  may 
climb  a  cliff  wall  of  a  canyon,  then  walk  for  a  distance,  often 
miles,  to  a  second  line  of  cliff's,  which  he  climbs,  and  can  pass 
over  comparatively  level  land  for  a  distance,  more  or  less,  until 
another  line  of  cliffs  is  reached.  Thus  cliffs  rise  over  cliffs, 
forming  a  series  of  great  steps  from  terrat^e  to  terrace. 

Such  cliffs  are  not  regular  in  the  lines  of  their  faces.  The 
river  itself  is  meandering,  and  so  the  lines  of  cliffs  are  mean- 
dering. Then  lateral  streams  may' cut  through  tluMU,  running 
to  the  main  river,  and  break  tliem  with  canyons;  and  these 
lateral  canyons  also  are  expanded  into  valleys,  and  the  teiTaces 
are  thus  carved  into  blocks  with  retreating  walls.  The  second 
system  of  canyons  may  be  traversed  by  a  third  system,  and  the 
terraces  may  thus  be  carved  in  many  ways;  and  as  the  process 
of  degradation  goes  on,  the  terraces  may  ultimately  be  gi'eatly 
obscured,  and  at  last  carved  into  hills  of  circumdoniidation, 
which  are  huttcs ;  and  finally  the  beds  may  be  rcdviced  to 
monuments  and  bowlders  of  rock;  but  canyon  walls,  teiTace 
faces,  buttes,  and  monuments  of  cliff"  structure,  remain  until 
the  region  is  brought  down  to  low  hills.  The  canyons  them- 
selves are  features  of  grandeur;  the  cliffs  are  conspicuous  for 
strange  and  fantastic  majesty ;  the  buttes  present  lone,  tower- 
ing forms  that  chaUenge  admiration;  and  the  monuments  may 
appear  like  gigantic  forests  of  stone  tree  trunks,  gnarled,  fan- 
tastic, and  picturesque. 

Valleys  sometimes  extend  back  into  high  plateaus.    TMieu 


50 


PHYSIOGRAPHIC   FEAXrRES. 


the  upper  surface  of  such  a  plateau  is  of  hard  rock,  and  the  rocks 
beneath  are  soft,  the  head  of  the  valley  may  be  au  amphitheater 
whose  walls  are  dirt's.  Sometimes  the  traveler  may  aseeud  such 
a  valley  from  the  itlain  below  uutil  he  reaches  a  cliff,  when  the 
walls  must  be  scaled,  or  he  must  turn  to  one  side  and  climb  the 
hills,  to  reach  the  summit  of  the  plateau.  Such  amjihitheaters 
are  called  cores.  Valleys  heading  in  mountains  may  have  coves; 
when  they  are  refashioned  by  glaciers,  they  are  known  as  cirques. 
On  seacoasts  and  lake  shores,  sapping  is  carried  on  by  the 
waves,  and  cliffs  are  often  produced. 


A  Shore  C'lifiF  on  Chesapeake  Bay. 

DusTROPHic  Cliffs. — "WTien  gi-eat  blocks  of  land  are  severed 
by  gi-eat  faults,  and  tilted,  the  broken  faces  of  the  uplifted  edges 
of  the  blocks  stand  in  great  lines  of  cliffs.  Such  diastrophic 
cliffs  retreat  by  dt'gradation  through  the  agency  of  S!ipi)iug,  so 
that  they  are  finally  converted  into  gradational  cliffs,  with  all 
the  characteristics  of  cliffs  of  the  first  class. 

Often  they  are  complicated  in  another  manner.  The  fissures 
of  the  folds  by  which  the  blocks  are  displaced  may  give  vent  to 
lavas  which  modify  and  obscure  the  cliffs.  In  regions  of  this 
character,  which  are  quite  extensive  in  the  United  States,  many 
of  the  cliffs  of  diastrophism  are  thus  in  part  developed  into  slopes 


CLIFFS. 


51 


by  vulcanic  rocks  piled  against  them.  Usually  tlie  coulees  pour 
out  a  flood  below ;  but  coulees  may  be  piled  on  coulees,  until  at 
last  the  accumulation  of  lava  becomes  so  liigh  as  to  flow  over  the 
margin  of  the  terrace,  and  build  low  mountains  along  tlie  lines 
of  faults.  Occasionally  in  such  places  volcanic  cones  are  formed. 
Cliffs  of  Vulcanism. — Coulees  of  lava  pour  from  the  vent 
and  flow  down  the  slopes  of  mountains  and  plateaus.     Some 


Ejppt"' 


'^ 


A  Coulee  Cliff  in  New  Mexien. 

lavas  are  excessively  fluid,  and  flow  in  thin  sheets;  otliers  are  but 
slightly  fluid,  and  flow  in  thicker  sheets;  all  cool  as  they  flow, 
until  at  last  they  come  to  a  standstill.  Wlien  the  rock  ceases  to 
flow  in  this  manner,  the  lavas  behind  pile  upon  it ;  and  coulees 
are  often  formed  with  very  rough  edges,  which  i-onstitute  cliffs 
that  may  be  scores  or  hundreds  of  feet  high.     Such  cliffs  may 


rHYSIOGRAPHIC   FEATDJIES. 


also  be  undermined  by  sapping,  and  carried  back  nun-e  or  less, 
as  in  the  case  of  cliffs  of  degradation. 

Thus  -we  have  cliffs  of  (Iri/raddtioii,  cliffs  of  dhistrophism,  and 
cliffs  of  nihdiiidiH. 


SPECIAL  FORMS. 


BrTTEs. —  Scattered  over  the  land,  a  great  variety  of  special 
forms  and  minor  f(>atures  are  observed  which  add  beauty  to  the 
landscape,  and  interest  to  the  study  of  the  jdiysiognomy  of  the 


lluttc-  iRiir  till'  Sail  .Juan  Kivi-r,  Cnloiado. 

land.  Hills  are  found  with  more  or  less  precipitous  cliffs  or  steep 
slopes,  that  stand  alone  as  monuments  of  circumdeniidation. 
These  may  be  called  huitcs. 

Monuments.  —  ]\Ionuments,  or  pillars  of  rocks,  are  often  left 
standing  in  the  great  process  of  degradation  ;  for  capping  stones 
of  gi'eat  hardness  sometimes  furnish  protection  to  xmderlying, 
softer  beds.  Such  monuments  may  be  tens  or  scores  oi-  hun- 
dreds of  feet  in  height ;  and  where  grouped  in  large  areas,  they 
are  sometimes  called  "  monument  parks." 

Dike  AV.\lls. —  Sometimes  crevices  in  tiio  rocks  are  filled 
with  lavas  from  below;  then  the  lavas  cool  into  rocks  of  a  firmer 
textm-e  tlian  thos(>  of  the  adjacent  formations;  afterward,  by  deg- 
radation, the  softiT  rocks  on  either  side  are  carried  awaj%  and 
the  lava  rocks  stand  in  walls.  Lavas  intruded  in  this  manner 
are  called  dikes,  and  dike  walls  are  common  in  volcanic  regions. 


STREAM   CHANNELS.  53 

Volcanic  Necks. —  Volcanic  cones  are  often  composed  iu 
large  part  of  ashes,  cinders,  and  readily  disintegrated  coulees; 
but  the  throat  of  a  volcano  is  usually  coated  with  hard  material 
which  has  come  up  in  a  flood  from  below  and  formed  a  chimney 
lined  with  very  hard  rock,  and  Anally  these  chimneys  are  com- 
pletely filled  witli  hard  rock.  In  the  process  of  degradation  the 
exterior  and  softer  materials  are  carried  away,  and  the  filled 
chimneys  of  hard  rock  staml  as  tombstones  of  the  dead  vol- 
canoes.    These  are  called  volcanic  necks. 

BowxDEUS. —  In  the  corrasion  of  stream  channels  and  the 
excavation  of  valleys  and  the  degradation  of  hills,  bowlders  of 
harder  and  more  coherent  rocks  often  remain  behind,  while  the 
softer  materials  are  carried  away  by  the  waters.  Thus  the  land- 
scape of  hilly  regions  is  often  strewn  with  rocks  of  many  fantas- 
tic forms,  and  the  remnants  of  hills  and  ridges  often  lie  in  jjiles 
of  water-worn  bowlders. 

Great  floods  also  move  large  blocks  of  stone,  and  sometimes 
scatter  them  over  the  valleys ;  and  wherever  stream  channels 
have  much  declivity,  bowlders  line  the  banks  and  shores,  and 
along  the  channels  are  strewn  gi-avels  worn  into  rounded  forms 
by  being  rolled  about  in  the  rushing  waters. 

Glaciers  ai'e  great  agencies  in  distributing  rocks,  gravels, 
sands,  and  clays  over  surfaces  of  land,  as  they  silently  creep  on- 
ward, or  sometimes  move  in  more  rapid  progress,  to  the  sounds 
of  breaking  and  crushing  ice. 

In  the  vicissitudes  of  hill  making,  ledges  of  hard  rock  often 
protrude  through  the  mantle  rock. 

Thiis  in  varied  ways  the  rocks  give  charm  to  the  landscape. 
He  who  understands  the  sulgect  of  physiography,  and  who  has 
his  eyes  open  and  his  mind  receptive  to  the  teachings  of  nature, 
not  only  discovers  beautiful  forms  and  wonderful  compositions 
of  forms,  but  at  the  same  time  i-eads  a  lesson  of  the  processes  of 
nature  and  the  great  forces  silently  but  irresistibly  at  work  to 
fashion  the  earthly  home  of  man. 

STREAM   channels    AND   CATARACTS. 

Stream  Channels. — Wlien  the  fields  are  unplowed,  the  rains 
wash  away  comparatively  little  (>arth.  The  streams  flowing  in 
the  forests  are  held  in  the  grass  and  under  the  fallen  leaves,  and 
slowly  creep  away  to  feed  the  rivers  with  clear  water;  but  when 


54  PHYSIOGRAPHIC   FEATURES. 

man  comes  to  gi-ade  aiid  travel  his  highways,  aud  plow  aud 
excavate  for  his  many  purposes,  the  loosened,  unprotected  eai-th 
is  soon  swept  away  by  rains,  and  fed  to  the  streams.  Thus 
man  changes  the  aspect  and  regimen  of  the  rivers.  Some- 
times, for  various  reasons,  fields  are  abandoned ;  and  these  old 
fields,  destitute  of  their  foi-ests  and  channeled  with  furrows  and 
ditches,  soon  become  a  prey  to  rains,  aud  by  them  the  st>ils 
are  washed  away,  the  declivities  are  cut  by  a  ramification  of 
storm-water  channels,  while  small,  naked  hills  are  left  behind 
that  are  nearly  wt)rthless  for  agriciilture.  It  is  thus  that  man 
increases  the  floods  by  his  labors,  and  destroys  lands  by  his 
neglect.  All  declivities  can  be  injm-ed  by  careless  plowing, 
and  then  the  richer  soils  are  rapidly  borne  away. 

When  the  evaporation  in  any  region  is  almost  equal  to  the  pre- 
cipitation, no  streams  would  be  formed,  were  it  not  that  the  rains 
fall  occasionally  in  great  quantities  for  short  periods  of  time. 
"When  such  storms  come,  a  multitude  of  storm-water  streams  are 
produced,  which  are  soon  dried  up.  The  more  permanent  streams 
have  periods  of  comparatively  gi-eat  flood  and  great  drought. 
About  the  mountains  and  plateaus,  and  generally  on  the  highlands, 
there  is  greater  rainfall,  and  many  perennial  streams  are  found 
whose  waters  run  to  lower  lands,  where  the  rainfall  is  less.  Grad- 
ually such  streams  lose  a  part  of  their  waters  by  evaporation,  and, 
though  of  considerable  magnitude  in  highlands,  become  very  in- 
significant in  the  lands  below.  It  is  thus  that  many  creeks  and 
rivei's  in  the  western  portion  of  the  United  States  cany  a  greater 
volume  of  water  near  their  sources  than  near  their  mouths. 
As  such  streams  gradually  diminish,  the  winds  blowing  over 
desert  plains  drift  the  sands  into  theu*  channels,  and  greatly 
choke  them.  The  water  coming  from  above  into  such  sands 
spreads  thi-ough  them,  and  is  evaporated.  Where  this  is  the 
case,  such  regions  of  evaporation  at  the  end  of  dying  streams  are 
called  sinks.  Below  such  sinks  the  channels  may  often  be  lost 
for  a  loDg  time.  Maximum  storms  come  sometimes, — years 
apart,  ten,  twenty-five,  or  a  hundred  years,  as  the  case  may  be, — 
and  by  these  great  storms  the  sinks  are  sometimes  washed  out, 
and  the  channels  below  opened  again,  and  the  rivers  once  more 
flow,  to  be  filled  again  during  long  periods  of  more  evenly  dis- 
tributed rainfall.  Such  buried  stream  channels  are  common 
throughout  the  western  half  of  the  United  States,  and  have 
caused  great  wonder  to  people  who  do  not  xmderstand  their 


CATAEACTS.  55 

origin  and  character.  As  the  streams  have  diminished,  the 
people  have  often  su])posed  that  the  chmate  was  changing,  and 
brought  in  evidence  the  fact  that  the  rivers  were  drying  up ;  or 
when  the  streams  have  been  opened  by  a  great  flood,  and  rivers 
have  appeared  where  they  seemed  not  to  have  existed  before,  the 
people  have  thought  that  the  climate  was  becoming  more  humid, 
and  promised  a  greater  supply  of  water  for  the  use  of  man. 

Many  of  the  streams  of  the  arid  I'egion  present  another  phe- 
nomenon of  great  interest.  Where  the  lands  are  arid,  the  streams 
must  have  steep  channels  in  order  to  corrade  deeply.  Many 
streams  have  a  declivity  which  would  be  considered  gi'cat  in 
humid  lands.  Streams  so  choked  by  dust  storms,  and  the  wash 
of  the  naked  lands  on  either  side  of  their  channels,  are  protected 
from  vertical  corrasion  by  the  accumulation  of  mud  upon  the 
channel  floors.  Under  these  circumstances,  lateral  corrasion 
prevails,  and  wide,  shallow  channels  are  produ(?ed.  Tliere  are 
streams,  like  the  Platte  or  the  iippcr  Arkansas  and  many  other's 
of  the  Great  Plains,  that  are  hundreds  of  yards  wide  and  only  a 
few  inches  in  depth  at  the  ordinary  stage  of  water,  and  never 
very  deep  at  the  highest  floods.  Such  rivers,  though  they  cany 
an  abundance  of  water,  are  not  navigable.  They  are  ever  loaded 
with  new  materials  by  floods  and  rains,  and  remain  turbid,  and 
often  are  rivers  of  mud  with  channels  beset  by  quicksands. 

From  the  explanation  which  has  been  given,  it  will  be  clear 
how  streams  carve  their  own  valleys.  In  studj'ing  the  history 
of  such  streams,  unless  all  the  facts  heretofore  set  forth  are 
properly  un<lerstood,  the  geogra])her  is  apt  to  err  in  sup- 
posing that  the  great  valleys  are  to  be  explained  in  another 
manner.  It  has  often  been  supposed  that  they  give  evidence 
that  in  a  time  long  past  the  rainfall  was  greater,  and  that  by- 
secular  change  the  climate  has  been  transformed  from  a  more 
humid  to  a  more  arid  condition,  and  that  with  the  transformation 
the  streams  have  gradually  become  less  and  less.  Such  errors 
have  gradually  disappeared,  as  the  methods  of  stream  cutting 
have  come  to  be  more  clearly  imderstood.  Thus  flood  plains, 
old  channels,  terraces,  and  retreating  cliffs  are  now  understood 
to  be  caused  by  the  streams  in  a  long  history  of  valley  making, 
and  they  are  no  longer  believed  to  furnish  e\adeuce  of  gi-eater 
rainfall  in  antiquity. 

Cataracts.  Gradational  Cataracts. — We  have  already  seen 
that  streams  have  short,  rapid  reaches  that  intervene  between 


56  PHYSIOGRAPHIC  FEATURES. 

loiig,  quiet  reaches.  These  short  reaches  are  mainly  due  to  the 
hard  rocks  which  compose  their  chauuels.  In  the  corrasion  of 
these  rapid  reaches,  the  tendency  is  to  cut  out  the  channel  at  the 
lower  end  of  the  reach  to  the  base-level  of  the  more  quiet  waters 
below.  This  tendency  is  accented  by  another  condition :  if  the 
quiet  waters  above  the  rapid  are  expanded  into  a  bi-oad  channel, 
and  especially  when  lakes  are  formed,  the  sediment  carried  by 
the  river  is  deposited  before  reaching  the  rapid.  More  and  more 
this  sediment  is  deposited  as  the  iipper  cpiiet  reaches  are  ex- 
panded into  lakes,  so  that  the  current  is  almost  wlioUj-  checked. 
The  load  or  sediment  which  the  waters  contain  is  the  instrument 
of  corrasion;  and  when  this  instrument  is  lost  in  the  quiet  waters, 
corrasion  is  checked.  The  waters  flowing  from  the  lake  above  are 
comparatively  pure,  and,  disarmed  of  the  weapons  of  corrasion, 
they  pour  into  the  rapid  reach.  Here  they  gather  new  sediments, 
and  aecunnilate  them  in  their  passage,  so  that  the  farther  they 
flow,  the  greater  the  amount  of  sediment  they  contain,  antl  the 
more  Adgorously  they  corrade.  Thus  the  rapid  reaches  are  cut 
down  progressively  from  below  upward. 

At  the  point  'where  the  rapid  waters  meet  the  quiet  reach 
below,  an  elbow  of  declixaty  is  formed,  at  the  Ijottom  of  which 
an  excavation  is  made ;  and  this  basin  holds  a  comparatively 
large  body  of  water,  which  is  kej^t  in  motion  by  the  stream 
rolling  down  from  above.  The  water  of  this  basin,  ever  stirred 
into  activity,  is  constantly  undermining  the  rocks;  and  the 
disintegrated  material  is  loaded  on  the  water  and  carried  away, 
to  be  deposited  not  far  below.  As  the  basin  retreats  upstream, 
it  steadily  enlarges,  and  an  incipient  cataract,  or  a  cascade,  is 
soon  produced,  the  fall  of  which  increases  from  stage  to  stage. 
Now,  if  this  basin  is  in  soft  rock,  as  in  clays  or  shales,  while  the 
rocks  above  are  hard, — a  condition  often  found, — then  the  rapid 
reach  cuts  back  and  increases  the  distance  of  the  fall  until  a  cat- 
aract is  developed.  Most  of  the  great  cataracts  of  the  world  are 
formed  in  this  manner,  the  two  most  important  conditions  being, 
first,  that  the  basin  should  be  in  soft  rock,  and  the  fall  over  hard 
rock;  and,  second,  that  the  waters  should  be  ponded  above  in 
order  that  the  instrument  of  corrasion  should  be  deposited,, and 
thus  permit  the  action  to  be  carried  on  chiefly  by  sapping. 

There  is  a  condition  under  which  cataracts  of  great  altitude 
are  produced,  though  they  usually  carry  but  small  (piantities  of 
water.    Wlien  the  great  streams  carve  canyons,  and  small  streams 


FOUNTAINS. 


57 


A  Ciitarai't  in  (ii'orgiii. 


enter  these  canyons,  the  rate  of  eorrasion  of  tlie  great  stream  may 
gi'eatly  exceed  that  of  the  small  stream ;  and  thus  most  interest- 
ing little  cataracts  are  formed,  which  often  Invak  into  si)ray 
before  reaching  the  floor  of  the  canyon,  and  their  own  coi-i'asion 
is  thus  largely  prevented.  Streams  of  water  woven  into  a  fili- 
gree of  spray  in  this  manner  are  often  called  hrklal  veils. 

DiastropMc  Cataracts. — When  streams  flow  across  faults  or 
monoclinal  flexures  that  are  in  process  of  displacement,  rapids 
and  often  well-developed  falls  are  pi'oduced ;  but  such  catai'acts 
have  a  short  existence.  ^\liere  the  condit  ions  are  favorable,  they 
speedily  cut  1  )ack,  and  become  falls  of  the  flrst  class. 

VHJcank  Cataracts. — Coulees  of  lava  freqi;ently  pour  across 
streams,  and,  cooling,  dam  the  waters  back  in  ponds  and  lakes. 
Under  such  conditions  cataracts  are  formed.  A  few  of  the  gi'eat 
cataracts  of  the  woi'ld  are  of  this  character. 

Thus  we  have  c/radatioi/al  cataracts,  diastrnphic  cataracts,  and 
vulcanic  cataracts. 

FOUNTAINS. 

Springs. — Water  and  air  both  circulate  through  the  mantle 
rocks,  which  are  in  the  main  rather  loosely  aggi-egated.     The 


58  PHYSIOGRAPHIC   FEATURES. 

igneous,  sedimentary,  and  metamorpbie  rocks  are  broken  into 
fragments,  large  or  small,  by  faults  and  joints,  so  that  there 
is  a  circulation  of  water  and  air  throiigb  them  also.  This  un- 
derground water  comes  to  the  surface  in  i^2^ri>i(/s  on  low  ground, 
as  on  the  sides  of  hills,  in  valleys,  and  in  the  banks  of  streams ; 
and  as  the  water  is  supplied  cm  the  surface  of  the  ground,  it 
finds  its  way  down  and  out  by  great  numbers  of  springs,  but 
it  must  be  understood  that  the  supply. is  primarily  derived  from 
the  clouds. 

Mammoth  Springs. —  Where  there  are  great  accumulations 
of  sand  and  gravels,  forming  hills  and  ridges  many  square  miles 
in  extent,  underlaid  by  impervious  formations,  mammoth  springs 
are  sometimes  developed.  The  rain  falling  upon  the  surface  sand 
percolates  to  harder  rock  below.  Thus  rills  and  brooks  are  formed 
on  the  upper  sm-faee  of  the  hard  rock,  below  the  sands.  Brooks, 
creeks,  and  even  small  rivers  may  be  formed  in  this  manner,  and 
may  issue  in  valleys  as  mammoth  springs.  In  such  a  case  a 
single  spring  may  give  rise  to  a  river  large  enough  to  float  a 
steamboat,  the  head  of  the  river  being  a  great  spring. 

In  volcanic  districts  great  accumulations  of  cindei's,  espe- 
cially in  mountain  cones,  present  the  conditions  favoring  the 
fonnation  of  such  mammoth  springs. 

Hot  Springs.  —  In  regions  where  the  rocks  at  and  near  the 
smface  are  of  late  volcanic  origin,  so  that  the  rocks  are  still  hot 
at  a  moderate  depth,  the  waters  circulating  through  the  fissm'es 
reach  these  hot  rocks,  and  hot  sjirings  are  formed. 

Geysers. —  Sometimes  steam  accumulates  in  reservoirs  of 
water  below,  until  it  explodes,  and  the  waters  are  exi^elled  with 
violence  in  intermittent  bm-sts.  Such  hot  springs  are  called 
geysers. 

Hot  water  is  a  gi'eat  solvent,  and  it  usually  reaches  the  sur- 
face strongly  charged  with  mineral  matter  from  the  rocks  through 
which  it  has  passed.  Cooling  in  the  open  air,  the  water  deposits 
much  of  its  dissolved  matter,  which  often  accumulates  about  hot 
springs  and  geysers  in  mounds,  and  decorates  basins  and  terraces 
with  beautiful  filigi-ee  forms. 

Wells. — Wells  are  dug  into  the  rocks  to  tap  the  under- 
ground waters.  Waters  gathered  in  such  reservoirs  are  mainly 
derived  from  the  loose  rocks  of  the  mantle,  but  sometimes  wells 
are  sunk  into  strata  pei'\nous  to  water.  All  such  waters  dissolve 
the  soluble  materials  of  rock,  especially  limestones  and  iron  ores. 


CAVERNS. 


5!) 


Hilt  springs  of  the  Vellowstone  Park. 

Waters  charged  with  hme  are  nsxially  said  to  be  hard,  while 
waters  charged  with  iron  are  called  chalj/hedtc. 

Aktesian  Wells.  —  Hometimes  a  supply  of  water  is  dis- 
covered in  this  mauuer,  whose  source  is  iu  distant  rocks  that 
come  to  the  surface  at  higher  levels,  and  the  hydraulic  pressure 
therefrom  causes  the  water  to  flow  over  the  mouth  of  the  well. 
Such  are  artesian  wells.  The  pressure  may  be  so  great  as  to 
throw  a  column  of  water  high  into  the  air.  A  spouting  well  is 
a  fountain  of  clear  water  and  a  fountain  of  beauty. 


CAVERNS. 

Gradation AL  Caverns. — It  has  already  been  seen  that  waters 
percolating  in  hills  and  mountains  dissolve  certain  rocks.  Where 
this  action  goes  on  above  the  base-level  of  the  country,  such  run- 
ning waters  flow  out  by  springs,  and  are  carried  away  by  streams. 
Underground  streams  are  formed  in  this  manner,  that  carve 
underground  channels,  which  are  enlarged  by  the  action  of  the 
waters  in  dissolving  their  walls.  Thus  caves  are  formed.  When 
a  stream  comes  through  some  harder  rock  of  limestone,  and 
reaches  a  soft  sandstone  that  easily  washes  away,  the  limestone 
is  undermined  as  the  sandstone  is  carried  away.    Then  channels 


60  PHYSIOGRAPHIC  FEATURES. 

liaWiig  underground  streams  may  be  produced  on  a  grand  scale, 
in  part  in  the  sandstone  below,  and  in  part  in  the  fissured  lime- 
stone above.  In  this  manner  great  separate  chambers  are  formed 
in  the  limestone,  with  communications  below  in  the  sandstone. 
Such  is  the  structure  of  Mammoth  Cave. 

In  the  walls  of  canyons  and  in  cliffs  formed  by  all  jirocesses, 
caves  are  produced  by  sapping.  The  softer  materials  below 
weather  out  and  are  carried  away  by  water,  and  the  harder  rocks 
above  are  left  as  overhanging  ceUings. 

Grottoes  of  this  character  are  often  very  Iteautiful,  and  are 
sometimes  roofed  amphitheaters  large  enough  to  shelter  regi- 
ments of  men.  Sometimes  springs  issue  from  such  eaves  and 
take  active  part  in  their  production ;  and  lakelets  may  be  formed 
which  are  fountains  of  cool,  crystalline  water.  In  arid  lands 
the  vegetation  springing  up  about  such  springs  is  luxuriant, 
while  in  humi,d  lands  the  mouths  of  caves  are  often  portals 
festooned  with  lichens,  liverworts,  mosses,  and  many  beautiful 
flowering  plants. 

Vulcanic  Caves. —  Caves  are  often  found  under  coulees  of 
lava,  for  the  soft  earth  is  easily  washed  away. 

Sometimes  the  streams  of  lava  are  very  fluid,  and  cool  at  the 
bottom  and  upper  surfaces  much  more  rapidly  than  in  the  inte- 
I'ior.  The  rocks  thus  formed  remain,  while  the  interior  molten 
lava  flows  on,  and  caves  are  formed  in  this  manner  which  are 
known  as  volctDt'ic pipes. 

Thus  we  have  gradational  and  vulcanic  caverns. 

LAKES. 

Of  the  rain  which  falls  upon  the  earth,  a  part  is  evaporated 
and  a  part  gathered  into  streams.  Along  the  courses  of  many 
streams  there  are  basins,  which  gather  the  water  in  lakes  where 
another  part  is  evaporated. 

If  these  l)asius  overflow,  the  waters  of  the  lakes  are  sweet ; 
but  if  they  have  no  outlet,  the  waters  are  salt.  Much  water 
evaporates  from  every  lake ;  and  if  the  surface  is  so  great  as  to 
give  an  evaporating  area  suflficient,  or  more  than  sufficient,  to  dry 
up  all  the  waters  coming  down  in  the  streams,  then  no  outlet  is 
necessary  or  possible.  But  the  waters  coming  from  the  land  dis- 
solve its  salts,  and  carry  them  into  these  lakes ;  and  as  the  waters 
escape  by  evaporation,  the  salts  remain.    Thus  gi-eat  accunufla- 


MAKSHES.  61 

tions  of  common  salt  gather  iu  the  lakes  of  arid  regions,  and  hence 
their  waters  are  saline.  We  must  learn  how  these  basins  which 
hold  the  lakes  are  formed. 

DiASTROPHic  Lakes.  —  In  the  displacement  of  the  crust  of  the 
earth  by  faulting  and  wrinkling,  depressions  are  made,  and  into 
these  basins  the  waters  are  gathered  by  streams,  and  lakes  are 
formed.  Most  of  the  great  lakes  of  the  world  are  of  this  charac- 
ter.    Let  us  call  them  diastrophic  lakes. 

Coulee  Lakes.  —  Sometimes  volcanic  lavas  are  poured  across 
valleys,  and  thus  the  channels  of  rivers  are  dannned.  These 
volcanic  dams  are  common,  and  some  rather  important  lakes  are 
formed  in  this  manner.  Geologists  call  a  sheet  of  lava  a  coulee. 
Let  us  call  such  lakes  coulee  lakes. 

Cratee  Lakes. — Occasionally  lakes  are  found  in  the  craters 
of  extinct  volcanoes.  Crater  Lake  of  Orego^i  is  a  beautiful 
illustration,  and  there  are  several  such  lakes  iu  the  nortlnn'u 
part  of  Arizona. 

Bayou  Lakes. — At  great  flood  times,  rivers  may  leave  their 
channels  and  cut  new  ones,  and  afterward  the  old  channel  may 
be  closed  in  such  a  manner  as  to  form  sites  for  lakes.  Let  us 
call  these  hayou  lakes. 

Glacial  Lakes. — Glacial  rocks  make  dams  across  vaUeys,and 
glaciers  carve  basins.  Wlien  a  region  of  country  is  redeemed 
from  the  glacial  condition  by  the  melting  of  the  ice,  such  basins 
are  filled  with  water,  and  lakes  are  formed.  In  the  northern  parts 
of  the  United  States  a  gi-eat  many  of  the  smaller  lakes  are  of  this 
character,  and  many  such  lakes  are  found  in  the  Rocky  Moun- 
tains.    Let  us  call  them  r/Iac/al  lakes. 

Thus  we  have  diastropliic  lakes,  coulee  lakes,  crater  lakes, 
bayou  lakes,  and  glacial  lakes. 

MARSHES. 

Hillside  Marshes. — It  has  previously  been  shown  that  the 
mantle  rocks  creep  down  the  slopes  of  hill  and  mountain. 
Where  the  grounds  are  favorable  for  their  retention,  they 
often  accumulate  to  a  gi-eater  or  less  thickness.  Into  such 
accumidations  the  waters  percolate  from  the  rocks  on  the  slope 
above,  and  from  the  I'ains  that  fall  on  their  surfaces.  In  such 
manner  hillside  and  mountainside  marshes  are  produced,  which 
are  often  called  hoys,  and  are  quagmires  which  tremble  under  the 
tread  of  man,  and  in  which  many  hoofed  animals  are  caught. 


62  PHYSIOGEAPHIC  FEATURES. 

Gi-eat  accumulations  of  this  general  character  sometimes  have 
their  lower  portions  carried  away  by  gradual  degi-adation,  when 
their  marshy  contents  j-ield  to  the  force  of  gi'avity  and  escape  to 
a  region  below.  Such  movements  are  called  laiidslides.  They 
are  often  destructive  to  hamlets,  gardens  and  fields,  and  some- 
times to  domestic  animals  and  human  life.  "Wlien  lakes  are 
drained,  their  old  beds  often  become  marshes  in  which  rank 
vegetation  may  accumulate  to  fonn  jycat.  About  the  margins 
of  lakes  extensive  marshes  are  sometimes  found. 

Flood-pl-ain  Mahshes. — We  have  seen  how  flood  plains  are 
gi-aded  by  the  overflo^ving  water  of  streams.  The  surface  left  is 
more  or  less  irregular,  and  depressions  often  exist  where  marshes 
are  formed,  and  peat  sometimes  accumulates.  Where  flood 
plains  are  broad,  the  lands  adjacent  to  the  rivers  are  often  higher 
than  the  lands  farther  back.  These  low  gi-ounds  nearer  to  plains 
and  hills  often  become  the  sites  of  marshes ;  and  it  may  be  ob- 
served that  marshes  sometimes  sejiarate  good  agricultural  lands 
near  a  stream  from  hilly  lands  farther  away. 

Coastal  Mabshes. — Coast  regions  sometimes  sink  and  be- 
come marshes, or  rise  out  of  the  sea  to  form  marshes;  other  coasts 
are  degi-aded  until  they  become  marshes ;  still  other  coasts  are 
enlarged  by  the  accretion  of  sediment  to  their  margin;  while 
fringing  islands  are  produced,  and  marshes  are  formed  between 
such  fringing  islands  and  the  mainland.  These  coastal  marshes 
are  flooded  by  tides  with  the  salt  water  of  the  sea,  and  they  are 
also  flooded  by  the  fresh  water  of  the  streams  that  come  from  the 
land.  By  this  cai;se  their  waters  are  often  brackish.  Where  the 
zone  of  marsh  is  \\ide,  the  salt  water  sometimes  becomes  fresher 
and  fresher  from  seaward  to  landwai'd.  In  a  few  regions  the  salt 
water  is  clearly  demarcated  from  the  fresh  water,  for  certain 
trees  and  other  plants  grow  with  great  luxuriance  in  brackish 
water ;  and  as  they  die  and  fall  to  the  gi-ound,  they  are  filled 
with  shells,  the  shards  of  animals,  and  to  some  extent  with 
sediments,  itntil  a  bank  or  di\'ision  is  established  between  the 
waters  of  the  ocean  and  the  waters  of  the  land. 

coast  forms. 

Gulfs,  Bays,  Sounds,  xsd  Straits. —  The  seacoast  and  lake 
shores  of  a  sinking  land  are  often  deeply  indented  with  bodies 
of  water,  while  the  shores  of  a  rising  land  are  more  regular. 


ISLANDS.  G;J 

The  islands  that  stand  before  the  land  add  niudi  to  this  ir- 
regularity. Behind  the  islands  and  within  the  indented  coast, 
gulfs,  hays,  sounds,  and  straits  are  found.  These  terms  are 
used  in  a  very  confused  manner.  There  is  a  tendency  to  call 
the  larger  bodies  gulfs  and  the  smaller  bodies  bays,  while 
there  is  the  same  tendency  to  call  the  larger  connecting  bodies 
sounds,  and  smaller,  narrow  connecting  bodies,  sti'aits.  lender 
these  circumstances,  no  classification  by  varieties  can  be  made, 
but  only  the  tendency  of  usage  can  Ije  jjointed  out.  All  of  these 
bodies  may  be  classified  as  rulranic,  diastrophir,  and  (/railatioiial. 
Pkomontoeies,  Capes,  Peninsulas,  and  Isthmuses. — High 
points  of  land  extending  into  the  sea  are  often  called promoiitofies, 
lower  points  are  often  called  ca/pcs,  and  points  nearly  cut  off 
from  the  mainland  are  often  called  jjciiiiisHtas,  while  the  necks 
which  connect  peninsulas  with  larger  bodies  of  land  are  often 
called  isthmuses ;  Ijut  there  is  no  very  well  estalilished  usage  for 
these  terms,  and  the  nomenclature  is  rathei-  indefinite.  All  these 
forms  may  be  classified  in  the  three  gi'eat  categories. 

ISLANDS. 

Vulcanic  Islands. — When  fires  break  forth  to  pour  their 
floods  of  lava  into  the  waters,  they  may  l)uild  up  nilraiiir 
islands.  In  tropical  lands  such  islands  arc;  often  fringed  with 
coral  reefs. 

Bakiuer  Islands. —  Lakes  have  a  special  class  of  islands  not 
found  in  the  sea.  When  coulee  lakes  are  formed,  and  valleys  are 
filled  with  water,  the  higher  portions  of  the  valleys  often  remain 
as  islands.     Thus  we  have  tiarricr  islands. 

Diastrophic  Islands.  —  When  lands  sul)side  beneath  the  sea, 
higher  portions  may  be  left  as  islands.  Thus  we  have  islands  of 
subsidence,  and  we  may  call  them  doin/throw  islands.  In  the 
same  manner,  when  sea  bottoms  are  lifted  above  the  level  of 
the  ocean  by  diastrophic  agency,  in  wrinkling  or  faulting,  the 
higher  i)ortions  may  first  appear  as  islands.  Thus  we  may  have 
islands  of  upheaval,  and  call  them  iiplif}  islands. 

Gradational  Islands. — When  the  detritus  is  brought  down 
from  the  land  l)y  streams,  it  is  carried  into  the  sea,  and  by 
the  currents  distributed  along  the  shore,  and  mingled  with 
the  detritus  formed  by  the  Ijeatiug  waves.  In  this  juanner 
such  detritus  islands  are  often  formed.  They  may  be  called 
frinffing  islands. 


G4  PHYSIOGRAPHIC   FEATURES. 

A  siuking  land  is  itself  cut  into  bills  and  vallej's.  As  it  goes 
down,  the  valleys  are  filled  with  water;  and  the  hills  may  re- 
main as  islanils,  or  may  prosoiit  an  irregular  line  of  shore  to  the 
sea.  The  waves  continually  encroach  on  this  shore.  Where  the 
rocks  are  soft,  the  wear  is  rapid;  where  the  rocks  are  hard, 
the  wear  is  slow.  The  inlets  formed  by  subsidence  are  enlarged 
by  the  encroaching  sea.  Two  such  inlets  lying  somewhat  parallel 
to  each  other  may  send  out  arms  into  opposite  sides  of  a  tongue 
of  land ;  and,  as  these  anus  extend  backward,  they  may  finally  cut 
off  portions  of  the  land  and  form  islands.  These  may  be  called 
(julf-vnt  islands. 

Streams  sometimes  change  their  channels  at  flood  time,  new 
channels  being  cut ;  and  islands  are  thus  formed  between  the 
old  and  the  new  river  ])eds,  and  remain  as  such  until  the  old 
channels  are  filled  or  blocked,  so  as  to  become  lakes.  Such  cut- 
off islands  are  very  common  about  the  deltas  of  great  streams. 
Thej^  may  be  called  rirrr-ciif  islands. 

Again,  when  lakes  are  formed  by  glaciers  and  the  lowlands 
flooded,  the  hills  may  remain  above  water  as  islands.  Thus  we 
have  glacial  islands. 

An  attempt  has  been  made  to  characterize  the  physiographic 
features  of  the  earth,  mainly  as  they  are  dependent  upon  the 
three  great  physiographic  processes,  and  to  show  how  fire, 
earthquake,  and  flood  have  been  involved  in  fashioning  the 
land  and  sea. 


PHYSIOGRAPHIC  REGIONS  OF  THE 
UNITED   STATES. 


By  J.  W.  Powell. 


Of  a  countrj^  so  large  as  the  United  States  no  adequate 
physiographic  description  can  be  given  within  the  limits  of  a 
monograph  of  this  size.  The  purpose  here  is  to  define  the  great 
slopes,  and  then  a  greater  number  of  physiogi-aphie  regions, 
which  are  again  divided  into  districts,  and  to  indicate  some  of 
their  more  important  characteristics.  Three  of  the  regions  have 
been  selected  for  a  somewhat  more  elaborate  description, — one 
of  plains,  one  of  plateaus,  and  one  of  mountains,  —  thus  illus- 
trating briefly  all  three  tyjjes.  These  regions  are  the  Atlantic 
Plains,  the  Colorado  Plateaus,  and  the  Pacific  Mountains,  taking 
the  eastern,  a  midland,  and  the  wc^stern  region. 

It  will  be  noticed  that  an  old  custom  of  describing  great 
physiographic  regions  in  units  of  basins  has  not  been  followed. 
Against  that  plan  there  are  insuperable  objections.  Where 
there  are  large  rivers,  there  are  large  basins,  and  such  are  again 
subdivided  into  ever  smaller  and  smaller  basins;  and  where 
there  are  oceans  and  gulfs,  there  are  many  small  disconnected 
basins;  so  that  the  basin  unit  divides  the  country  into  very  un- 
equal parts,  and  fails  to  exhibit  the  association  of  great  features 
that  are  intimately  connected  in  physiographic  history.  Grad- 
ually, as  the  new  science  of  physiography  has  grown,  physio- 
graphic regions  have  come  to  be  recognized;  and  an  attemi)t  is 
here  made,  by  map  and  verbal  description,  to  define  the  princi- 
pal regions  of  the  United  States,  exclusive  of  Alaska. 

Tlie  regions  here  delineated  are  held  to  be  natural  divisions, 
because  in  every  case  the  several  parts  are  involved  in  a  com- 
mon history  by  which  the  present  physiogi'aphic  features  have 

(Copyright,  1895,  by  American  Book  Company.) 
65 


66  PHYSIOGRAPHIC    REGIONS   OF   THE   UNITED   STATES. 

been  developed.     They  have  been  characterized  by  the  more 
proniiiieiit  features  used  iu  the  name. 

In  dividing  the  United  States  into  a  few  great  physiographic 
regions,  it  is  not  found  possible  always  to  draw  the  lines  with 
exactness.  Often  one  region  blends  with  another,  the  transfor- 
mation in  general  characteristics  being  marked  by  a  general 
change.  There  are  some  lines  of  division  clearly  drawn  by 
nature  within  narrow  limits;  other  divisions  are  imperfectly 
marked  by  slow  gi-adation  from  one  to  the  other. 

DRAINAGE    SLOPES. 

The  United  States  may  be  divided  into  four  great  slopes, — 
the  Atlantic,  Great  Lake,  Gulf,  and  I'aci/ic.  All  the  streams  of 
the  Atlantic  slope  drain  into  that  ocean  by  river  mouths  within 
our  territory.  All  the  streams  of  tlie  Great  Lake  slope  ulti- 
mately discharge  into  St.  Lawrence  River  within  our  own  terri- 
tory. To  the  north  another  region  not  within  our  domain  is 
drained  into  that  river,  which  ultimately  discharges  into  the 
Atlantic  Ocean.  This  larger  division  is  therefore  but  partly  in- 
cluded within  the  L^nited  States.  The  Gulf  slope  includes  all  of 
our  territory  drained  into  the  Gulf  of  Mexico.  In  popular  usage, 
most  of  this  is  called  the  valley  of  the  Mississippi,  while  small 
areas  are  drained  into  the  Gulf  by  streams  not  tribiitary  to  the 
great  river ;  and  in  the  southwest  there  is  a  district  drained  by 
the  Rio  Grande  del  Norte,  which  heads  in  central  Colorado,  flows 
through  New  Mexico,  and  then  turns  eastward,  forming  the 
boundary  line  between  the  LTnited  States  and  the  Republic  of 
Mexico,  until  it  discharges  into  the  GuK.  Its  waters  only  in 
part  are  caught  on  the  soil  of  the  United  States:  it  is  a  very 
small  part  which  comes  from  Mexico.  Along  the  western  boi'der 
of  this  grand  division  the  country  is  arid,  having  a  rainfall  of 
less  than  twenty  inches  annually,  /n  this  arid  region  there  are 
many  small  streams  whose  waters  are  not  carried  away  by  ocean- 
feeding  rivers,  as  the  small  streams  are  lost  in  the  sands. 

On  the  Pacific  slope  all  streams  that  ultimately  run  to  the 
sea  reach  the  Pacific  Ocean  mainly  within  the  territory  of  the 
United  States;  but  the  district  drained  by  the  Colorado  River 
of  the  West  reaches  the  Gulf  of  California  by  passing  a  short 
distance  tlirough  Mexican  territory.  In  a  large  part  of  the 
Pacific  slope  there  are  many  small  streams  that  discharge  their 


DRAINAGE    SLOPES.  67 

waters  into  sands,  where  they  are  evaporated  and  lost  from  the 
oceau-reaehiug  drainage ;  but  the  valk'vs  in  which  they  are  evap- 
orated incHne  toward  streams  draining  into  the  Pacific  Ocean. 

We  thus  have  an  Atlantic  slope,  a  Great  Lake  slope,  a  Gulf 
slope,  and  a  Pacific  slope;  aiid  these  terms  are  coming  into 
common  use  for  the  four  grand  divisions  of  the  United  States. 

An  examination  of  the  relief  map  of  the  United  States  pub- 
lished by  the  general  government  will  show  that  the  lines  of 
separation  between  these  great  slopes  are  very  irregular.  Every- 
where along  them  there  is  an  interosculation  of  head-water 
streams.  Between  the  Atlantic  slojie  and  the  Great  Lake  slope 
the  divides  are  sometimes  in  mountains  and  sometimes  in  hills; 
between  the  Atlantic  slope  and  the  Gulf  slope  the  meandering 
division  line  is  in  part  in  mountains  and  in  part  along  the  low 
peninsula  of  Florida;  between  the  Gulf  slope  and  the  Gi'eat 
Lake  slope  the  dividing  line  is  an  inconspicuous  elevation,  so 
low  in  many  places  that  the  waters  may  easily  be  diverted  from 
one  slope  to  another ;  and  in  late  geologic  time  this  change  has 
often  occurred,  and  a  part  of  the  drainage  of  the  trreat  Lakes 
has  been  turned  from  the  St.  Lawrence  into  the  Mississippi. 
The  ii-regular  divide  between  the  Mississippi  region  and  the 
Pacific  region  is  sometimes  mountainous,  with  peaks  varying 
from  eight  thousand  to  fourteen  thousand  feet  above  the  level 
of  the  sea.  The  Atlantic  slope  is  a  comparativ(>ly  uniform  d(>- 
chvity,  relieved  by  plateaus,  mountains,  and  hills  that  do  not 
rise  to  great  altitudes  above  the  base-levels  of  the  streams. 
With  slight  exception,  the  Great  Lake  slope  is  a  vast  plain 
broken  into  subordinate  plains  Ity  terraces  and  hills.  The  Mis- 
sissippi slope  has  the  Api)alachian  Mountains  on  the  east,  with 
declivities  for  its  streams  that  greatly  decrease  from  the  moun- 
tains to  the  river;  and  is  relieved  by  plateaus,  hills,  and  moun- 
tains with  great  altitudes  above  the  rivers  near  the  Appalachian 
and  Rocky  mountains,  and  has  low  reliefs  nearer  the  Mississippi. 
On  the  north  the  line  of  separation  from  the  Great  Lake  slope  is 
in  a  single  plain,  but  without  perfect  uniformity,  for  there  are 
many  terraces  and  hills.  On  the  west  the  rim  of  the  basin  is 
in  high  mountains  with  lofty  peaks,  and  all  along  its  western 
border  the  reliefs  are  of  comparatively  great  magnitude. 

The  Pacific  slope  is  in  the  great  Rocky  Mountain  region. 
The  Stony  Mountains  stand  on  its  eastern  border  at  the  north, 
separating  it  from  the  Missouri  drainage.    Here  towering  moun- 


68  PHTi'SIOGRAPHIC    KEUIONS    OF   THE    UNITED    STATES. 

taius  with  a  wildeiuess  of  erags  ami  peaks  appear,  over  which 
the  snows  are  mantled  for  many  mouths  of  the  year,  and  in 
whose  deep  gorges  he  perennial  snows.  Then  the  di\'iding  line 
extends  between  the  Platte  Plateaus,  drained  by  Laramie  River, 
and  the  upper  extension  of  the  Colorado  Plateaiis,  drained  by 
Green  River,  The  divide  is  in  the  Park  Mountains,  character- 
ized by  gi'eat  peaks,  and  extends  still  farther  southward  across 
the  Colorado  Plateaus,  and  down  the  Basin  Ranges  to  the  Mexi- 
can line.  On  the  flanks  of  the  Stony  and  Park  mountains  there 
are  many  volcanic  peaks  whose  fires  are  noAv  extinguished ;  still 
farther  westward  there  are  great  plateaus  and  mesas  carrying 
dead  volcanoes  on  their  backs ;  and  still  farther  westward  there 
are  many  ranges  of  mountains,  generallj'  extending  in  a  north- 
erly and  southerly  direction,  between  which  lie  gi-eat  valleys 
that  are  often  desert  jilains.  Then  we  reach  the  Sierra  Nevada 
at  the  south,  and  the  Cascade  Mountains  at  the  north,  which 
end  the  longitudinal  ranges  and  valleys.  The  Cascade  ^lountains 
are  mainly  volcanic  peaks  standing  on  huge  diastroi^hic  plateaus, 
while  the  Sierra  Nevada  is  a  great  complex  diastrophic  plateau 
carved  into  transverse  ridges  by  streams  that  head  on  its  eastern 
margin  and  run  westward  into  the  valley  of  California.  The 
ridges  between  these  east-and-west  streams  are  very  irregular, 
and  decline  in  altitude  from  the  east  toward  the  west.  In  the 
Cascade  Mountains  the  streams  also  have  a  general  westward 
direction  into  the  great  Sound  Valley ;  but  there  is  a  region 
which  separates  the  Sound  Valley  from  the  valley  of  California, 
known  as  the  Klamath  Mountains,  through  which  the  streams 
heading  in  the  southern  part  of  the  Cascade  region  and  the 
northern  jiart  of  the  Sierra  region  flow  to  the  sea  without  turn- 
ing into  the  rivers  of  the  gi'eat  valleys.  The  Sound  Valley 
within  the  United  States  is  only  a  portion  of  a  great  valley 
which  lies  partly  within  British  territory.  North  of  Columbia 
River  and  west  of  Sound  Valley  stand  the  Olympic  Mountains, 
and  south  of  that  river  stand  the  Oregon  coast  ranges,  some- 
times called  the  Oregon  Ranges.  Thus  tlie  Pacific  coast  is  ex- 
ceedingly complex  in  its  great  topographic  features. 

These  four  grand  divisions  present  interesting  characteristics 
and  contrasts,  due  chiefly  to  inequalities  of  rainfall,  wliich  pro- 
duce deserts,  prairies,  and  forests. 

Deserts. — Plants  require  great  quantities  of  water  for  their 
nourishment.      With   their   roots    they   drink   the   water,  and 


PllAIKIES   AND    FOKESTS.  69 

through  their  leaves  they  evaporate  it  to  the  heavens.  In  this 
process  a  very  small  proportion  is  used  by  the  plant,  and  built 
into  its  tissue.  To  gi-ow  a  ton  of  hay,  the  grass  plants  must 
drink  two  or  three  hundred  tons  of  water.  The  growth  of  vege- 
tation depends  very  largely  upon  the  regularity  with  which  the 
roots  of  the  plants  are  supplied  with  drink.  When  the  rainfall 
is  slight  and  periods  of  drought  are  great,  vegetation  is  scanty ; 
but  when  the  rainfall  is  abundant,  vegetation  is  more  luxuriant. 
Temperature  is  another  factor  in  the  rate  of  growth.  With  liigh 
temperature  and  gi'eat  rainfall,  the  most  vigorous  vegetation  is 
produced;  with  low  temperature  and  sliglit  rainfall,  more  scanty 
vegetation  is  found ;  but  if  the  rainfall  is  very  small,  high  tem- 
perature serves  rather  to  increase  aridity  and  the  desert  con- 
dition. In  tlie  temperate  zone,  if  the  rainfall  is  less  than  ten 
inches  annually,  the  desert  conditions  prevail ;  but,  though  the 
rainfall  may  be  less  than  five  inches  annually,  the  desert  will  yet 
afford  some  clas.ses  of  plants,  like  the  iigave,  yucca,  and  cactus. 

Many  desert  plants  are  covered  with  a  kind  of  bark,  the  poi-es 
of  which  close  in  times  of  aridity  so  as  to  prevent  their  water 
from  being  evaporated.  Other  ])lants  have  a  hal)it  of  rolling  up 
their  leaves  and 'folding  their  stems  in  such  a  manner  as  to 
present  the  smallest  surface  for  evaporation.  Nearly  all  desert 
plants  are  furnished  with  thorns,  and  many  with  acrid  juices 
that  protecit  them  from  being  devoured  by  animals.  So  the 
plants  struggle  for  existence.  The  animals  of  the  desert  are 
few,  though  some  insects  and  some  reptiles  abound ;  and  among 
them  many  cnrious  forms  may  be  observed. 

Deserts  are  l)eset  with  dunes  formed  of  wind-blown  sand. 
Sometimes  deserts  have  scattered  over  their  floors  pebbles, 
which  are  the  remnants  of  formations  carried  away  by  degrada- 
tion. They  are  worn  fragments  of  very  haixl  rocks,  often  crys- 
talline and  of  many  colors.  As  the  sand  sweeps  over  them,  the 
pebbles  are  polished,  and  the  desert  is  sometimes  floored  with  a 
mosaic  of  brilliant  gems. 

Prairies  and  Forests. — As  the  rainfall  increases  from  ten 
to  twenty  inches,  grasses  and  various  other  plants  are  multiplied, 
and  become  more  and  more  luxuriant;  and  low,  gnarled  trees, 
especially  cedars  and  pines,  are  developed,  if  they  arc  protected 
from  fires.  As  the  rainfall  increases  from  twenty  to  forty  inches, 
forests  increase ;  that  is,  they  are  extended  over  greater  areas, 
and  the  trees  themselves  have  a  more  rapid  growth,  and  attain 


70  PHYSIOGKAPHIC    REGIONS   OF   THE   UNITED   STATES. 

larger  size.  In  such  regions  ^ngorous  forests  will  gi-ow,  if  they 
are  protected  from  fire.  The  gi-eat  prairie  region  of  the  United 
States  is  found  mainly  where  rainfall  is  from  twenty  to  forty 
inches,  because  the  forests  are  destroyed  by  fire.  Going  from 
the  more  arid  to  the  more  humid  regions,  forests  become  more 
frequent  and  more  vigorous;  and  e8i>ecially  are  trees  found  near 
streams,  and  where  the  lands  are  hilly,  broken,  and  stony,  so  that 
luxuriant  grasses  are  not  abundant,  to  furnish  food  for  fire. 

Since  the  prairies  of  the  United  States  were  settled,  gi-eat 
changes  have  been  wrought  in  the  landscape.  Protected  from 
fire  by  the  plowman's  furrow,  trees  have  sprung  up  everj'where ; 
so  that  to-day,  throiigh  all  that  region  stretching  from  the  Ohio 
across  the  Mississippi  and  across  the  Missouri  on  to  the  Great 
Plains,  the  forest  areas  are  rapidlj'  nuiltiplyiug,  and  planted 
gi'oves  are  common.  It  is  thus  that  cultivation  protects  forests, 
and  furnishes  the  condition  for  foresting  lands  which  were  prai- 
ries in  their  primeval  state. 

When  man  attempts  to  preserve  lai'ge  forests  without  pro- 
tecting the  ground  with  the  plow  or  by  other  agencies,  he  usually 
fails.  To  save  the  forests,  he  carefully  tries  to  prevent  fires ;  then 
grass,  leaves,  bark,  twigs,  and  boughs  gather  upon  the  surface 
of  the  earth  from  year  to  year,  until  a  thick  coating  of  infiam- 
mable  material  is  formed.  Immunity  from  fire  thus  furnishes 
food  for  fire ;  and  when  a  dry  season  comes,  an  accidental  spark 
starts  a  great  conflagi'ation,  which  spreads  with  the  wind  as 
only  "wildfire"  spreads,  and  the  great  accumulation  of  combi;s- 
tible  matei'ial  makes  a  sweeping  flame  which  destroys  everything 
before  it.  It  is  thus  that  the  forests  of  the  Northwest,  which  are 
largely  held  for  lumber  purposes,  are  subject  to  fires  that  destroy 
property  on  a  great  scale,  and  even  destroy  human  life. 

Where  the  rainfall  is  sufficient  protection,  and  fires  are  not 
kindled,  forests  prevail.  In  soixthern  latitudes  and  low  altitudes 
the  trees  attain  a  greater  size  than  in  noi'thern  latitudes  and 
high  elevations;  but  there  are  some  important  exceptions  to  this 
general  rule.  In  Washington,  Oregon,  and  California,  gigantic 
forests  are  foi;nd  developed  by  humid  lands  that  lie  near  the 
Pacific  coast,  while  other  gi'oves  of  great  trees  stand  on  the 
slopes  of  the  Sierras  that  face  the  great  ocean.  Where  the  mois- 
ture is  more  than  fifty  inches,  and  where  other  climatic  condi- 
tions are  favorable,  dense  forests  of  gigantic  trees,  with  tangled 
masses  of  undergrowtli,   stretch  over  the  land.      In  the  great 


PRAIRIES   AND   FORESTS.  71 

valley  of  California,  live-oak  groves  abound,  and  the  trees  are 
gnarled  and  picturesque.  In  more  arid  lands,  groves  of  low, 
spreading,  gnarled  pinons  and  cedars  are  scattered  at  wide 
intervals.  In  early  time,  before  the  prairie  region  was  settled, 
there  were  found  groves  of  low,  spreading  l)ur-oak.s,  that  from  a 
distance  looked  like  orchards ;  and  in  fact  they  were  orchards  of 
acorns.  In  the  humid  lauds,  and  especially  in  the  tropic  lands 
of  Florida,  the  great  trees  are  often  draped  with  festoons  of 
"  Spanish  moss,"  and  decorated  with  beautiful  orc^hids.  In  the 
valley  of  the  Ohio,  magnolias  spi'ead  their  blossoms  as  goblets 
of  perfume.  All  over  the  Alleghany  Plateaus,  the  Appala«'hian 
Mountains,  and  the  Piedmont  Plateaus,  great  tulip  trees  stand, 
with  stately  boles  and  light  branches  that  bear  most  beautiful 
flowers.  In  every  flood  plain  of  the  I'^uited  States,  sycamores 
with  smooth  trunks,  broad  arms,  and  expanding  leaves,  spread 
a  sweet  shade  over  the  gi'ound  when  the  summer  sun  is  fien-e. 
By  every  river,  creek,  and  brook  t\n)  willows  stand,  and  dip  thoir 
delicate  leaves  into  the  nuirmuring  waters.  In  the  ponds  and 
lakes  of  the  United  States,  water  lilies  grow,  and  on  all  the  hill- 
sides roses  bloom.  Late  in  the  summer  tlie  goldenrod  Imrsts  into 
flame  along  the  northern  border  of  our  land;  and  as  tlie  weeks 
and  months  pass,  the  zone  of  gold  sweeps  southward  until  it  is 
stopped  by  the  Gulf. 

Before  the  settlement  of  America  by  the  P]uroi)eans,  while 
the  land  was  yet  under  the  sway  of  savage  tribes,  the  whole 
country  was  annually  burned  over,  ami  wherever  forests  could 
be  destroyed  they  W(*re  swejjt  away ;  but  when  the  lands  were 
plowed,  the  fires  were  stojjped ;  and  vast  regions  that  were 
prairies  at  that  time  ai'e  now  forest-clad.  To-day  the  forests  of 
the  United  States  are  somewhat  more  extensive  than  they  were 
at  the  landing  of  ('olumlnis.  While  the  prevention  of  fires  saves- 
some  trees,  the  ax  fells  others,  so  that  many  forest  r(>gions  have 
been  transformed  into  fields ;  yet  to-day  fli-es  destroy  more  trees 
than  the  ax. 

The  growth  of  trees  depends  upon  rainfall,  but  i>art  ly  also  upon 
care.  Seeing  that  arid  lands  are  treeless,  many  observers  reach 
the  conclusion  that  aridity  is  due  to  the  destruction  of  the  for- 
ests. The  (>ffe('t  is  nnstaken  for  the  cause.  This  superstition 
has  widely  prevailed,  and  many  of  those  who  have  not  studied 
this  subject  believe  that  rainfall  can  be  increased  by  the  planting 
of  ti'ees.     This  subject  has  l)een  most  carefully  and  thoroughly 


72  PHYSIOGRAPHIC    REGIONS   OF   THE    UNITED    STATES. 

iuvestigated  by  scioutifie  meu,  aud  they  are  not  able  to  discover 
that  the  presence  or  absence  of  trees  either  increases  or  dimin- 
ishes the  rainfall ;  and  yet  this  mj-th  is  told  all  over  the  land. 

On  the  Atlantic  slope  primeval  forests  were  discovered  in  the 
early  settlement  of  the  country,  and  a  few  of  the  valleys  were 
prairies.  Forests  were  mainly  open,  without  dense  under- 
growth, as  they  were  annually  burned  by  the  Indians.  Since 
the  settlement  of  the  country,  gi'eat  areas  have  been  cleared, 
and  prairies  have  been  brought  under  the  plow.  The  forest 
lands  that  remain  have  been  protected  from  fires,  the  under- 
growth is  preserved,  and  open  forests  are  no  longer  seen.  Here 
the  forest  area  is  smaller  than  at  the  advent  of  the  white  man, 
but  the  number  of  trees  is  nearly  as  gi'eat. 

The  Great  Lake  region  also  was  mainly  covered  with  forests 
when  the  country  was  settled  by  civilized  people;  but  the  groves 
were  open,  and  the  trees  were  comparatively  low  and  gnarled, 
as  they  were  ofteu  singed  by  fires.  The  primeval  forests  are 
nearly  gone,  much  of  the  country  is  under  the  plow,  but  the 
new  forests  present  changed  characteristics.  The  new  trees, 
densely  crowded,  compete  for  the  light  of  the  sun,  and  gi'ow  to 
greater  heights;  and  the  ground  below  is  covered  with  dense 
foliage  and  tangled  imdergrowth.  Here  also  the  forest  area  has 
been  reduced,  but  the  number  of  standing  trees  is  perhaps  as 
great  as  in  primeval  times. 

The  greatest  change  has  been  wrought  in  the  Mississippi 
slope.  Its  northern  and  central  portions  were  mainly  a  prairie 
region,  and  extended  to  the  foot  of  the  Rocky  Mountains.  The 
few  forests  to  the  north,  the  greater  wooded  regions  on  the 
flanks  of  the  Appalachian  Mountains,  and  the  more  imposing 
forests  on  the  south,  protected  from  fires,  have  increased  in  the 
•  number  of  standing  trees,  though  great  fields  have  been  cleared 
for  agriculture.  Throughout  the  prairie  region  the  river-border 
groves  have  become  more  dense,  and  the  trees  more  stately. 
From  these  groves  the  native  forests  have  spread  over  a  large 
aggregate  of  ground,  and  many  groves  and  orchards  have  been 
planted.  Though  this  prairie  region  is  densely  settled  and  much 
of  it  cultivated,  the  groves  have  lost  their  primeval  character, 
and  the  vigorous  trees  have  multiplied  to  an  astonishing  degi-ee. 

The  Pacific  slope  presents  great  contrasts  in  its  southern 
part,  where  there  are  extensive  areas  of  desert.  The  mountains 
and  high  plateaus  are  everywhere  covered  with  forests ;  and  on 


THE   ATLANTIC    PLMNS.  73 

the  slope  of  the  Sierras  groves  of  giant  sequoias  are  found,  while 
near  the  coast  towering  redwoods  appear.  In  western  Oregon 
and  Washington,  yellow  pines,  redwoods,  and  cedars,  and  many- 
other  stately  trees,  flourish  in  the  warm,  humid  lands  that  are 
supplied  with  moisture  from  the  Pacific.  On  the  Pacific  slopes 
we  have  dreary  deserts,  prairie  valleys,  and  gigantic  forests. 

THE    ATLANTIC;    PLAINS. 

A  monoclinal  flexure  extends  fi-om  iha  Jersey  side  of  Hudson 
River  near  the  city  of  New  York,  southwestward  i^ast  Trenton, 
Philadelphia,  Baltimore,  near  the  falls  of  the  Potomac,  above  the 
city  of  Washington,  where  the  line  curves  in  a  more  southerly 
direction  to  Kiclnnond,  Weldon,  Raleigh ;  and  turning  westward, 
it  crosses  Savannah  River  near  Augusta,  and  gradually  disap- 
pears in  the  region  of  Macon,  Ga.  This  geologic  feature  extends 
in  an  indefinite  way  past  Montgomery.  It  is  easily  followed  by 
the  geologist  from  New  York  to  IMacon,  past  the  streams  tliat 
flow  into  the  Atlantic,  until  streams  are  reached  which  faU  into 
the  Gulf  of  Mexico.  Tliis  line  of  disphicement  has  an  interest- 
ing geologic  history.  The  rocks  to  the  west  and  northwest  are 
of  Archaean  age;  the  rocks  to  the  east  and  soutliwest  are  mainly 
of  Cretaceous,  Eocene,  and  Neocene  age.  The  line  or  narrow 
zone  separates  hard,  dark,  crystalline  schists,  traversed  by  veins 
of  white  quartz  that  are  of  ancient  geologic  formation,  from 
gravels,  sandstones,  shales,  and  clays,  that  make  up  the  rocks 
of  later  origin.  Since  the  beginning  of  Cretaceous  time,  a  zone 
extending  from  the  monoclinal  flexure  to  the  sea  has  passed 
through  several  vicissitudes  of  history,  at  times  being  dry  land 
as  it  is  now,  and  at  times  being  sea  bottom.  So  the  shore  of  the 
sea  has  oscillated  slowly  back  and  forth  across  this  part  of  the 
Atlantic  Plain.  Along  tl|e  advam-ing  and  receding  coast,  gravels 
have  been  piled  by  streams  coming  from  the  landward  side,  and 
with  them  sands  and  clays  have  been  deposited ;  ])ut  the  finer 
materials  have  always  been  carried  farther  into  the  sea,  and, the 
coarser  materials  left  near  the  shore.  In  studying  the  rocks 
of  which  th(^  plain  is  composed,  as  they  are  t^xposed  in  stream 
banks  and  blulfs,  and  as  they  are  revealed  in  digging  and  boring 
wells,  alternations  of  gravel,  sand,  and  clay  are  discovered ;  and 
the  gravels  usually  increase  in  thickness  toward  the  northwest, 
and  thus  appear  to  be  shore  deposits  along  an  advancing  or  re- 


74  PHYSIOGIUPHIC   KEGIONS   OF  THE   UNITED   STATES. 

t'L'ding  coast.  Distinguished  so  clearly  by  geologic  features,  the 
topogi-aphic  characteristics  of  this  zone  are  even  more  plainly 
marked.  The  line  of  flexure  is  everywhere  more  or  less  clearly 
deliued  as  a  terrace  broken  by  valleys  and  stream  channels.  In 
the  streams  the  line  is  still  more  marked,  for  everywhere  they 
cross  it  in  rapids  and  falls.  Far  above  there  are  rather  swift- 
flowing  but  ([iiiet  reaches;  at  the  flexure  they  plunge  down  with 
rolling,  tui-bulcnt  currents,  and  fall  into  broad  channels  with 
placid  waters.  Below,  all  the  streams  of  magnitude  rise  and  fall 
with  the  tides ;  above,  all  the  streams  rise  and  fall  with  the  great 
storms ;  while  along  the  narrow  zone  of  flexure  the  clear  waters 
are  transformed  into  rushing  torrents  by  long-continued  rains. 
Here  we  find  the  gi-eat  water  powers  which  have  been  utilized 
ever  since  the  early  settlement  of  the  country ;  and  here  we  find 
the  barrier  to  navigation,  for  the  vessels  that  come  from  the 
Atlantic  coast  cannot  be  navigated  across  the  fall  line,  and  all 
boat  transportatioii  from  below  ends  here.  A  few  of  the  streams 
can  be  navigated  above  this  line ;  but  their  cargoes  must  be  car- 
ried over  the  fall  line  and  reshipped,  to  reach  the  sti-eams  below. 
The  zone  of  displacement  is  thus  marked  by  characteristics  which 
divide  the  country  above  from  the  coimtry  below  in  a  double 
way.  It  is  the  zone  of  water  powers  and  the  zone  of  interrupted 
trausjjortatiou  by  water.  Under  these  circumstances  the  fall  line 
was  well  marked  in  primeval  times,  evo  yet  the  white  man  had 
settled  in  the  land,  for  a  line  of  Indian  villages  extended  along 
it  from  the  Hudson  to  the  Savannah.  Later,  under  the  aegis  of 
civilization,  cities  were  built  at  this  line,  with  convenient  water 
power  for  manufacturing  purposes,  and  easy  means  of  commerce 
with  the  old  country  by  the  sea,  and  with  the  interior  by  rivers, 
canals,  and  roads.  Thus,  ^^ncousciously  to  the  savage  and  un- 
consciously to  civilized  man,  geologic  conditions  fixed  the  sites 
of  ancient  villages  and  modern  cities  at  the  head  of  tide  water 
and  in  the  region  of  the  great  water  powers.  From  this  fall  line 
a  great  plain  extends  to  the  coast,  jnarked  by  few  hills,  and 
slightly  terraced  witli  bluifs  on  the  margins  of  flood  plains. 
Near  the  coast  and  along  the  flood  plains  extensive  marshes  are 
found.  This  irregular  zone  of  marsh  is  clearly  distinguished 
from  the  higher  plain.  A  lower  plain  extends  from  the  coastal 
marshes  out  to  the  sea  for  many  miles,  until  at  last  shallow 
waters  change  into  deep  waters,  and  the  bottom  plunges  down 
Avith   steep  declivity  into  the   depths   of  the  Atlantic.      This 


THE   ATLANTIC   PLAINS.  10 

Atlantic  plain  is  therefore  naturally  divided  into  three  great 
zones, — the  subaerial  portion;  the  marsh  portion,  which  is  cov- 
ered more  or  less  intermittently  witli  water  by  tides  and  storms ; 
and  the  suhmaiine  portion,  which  extends  out  to  deep  waters. 

Above  the  city  of  New  York  the  marine  ijortion  of  the  plain 
expands,  while  the  marsh  portion  is  usually  narrow,  though  some- 
times it  extends  back  into  the  high  land  many  miles;  but  it  is 
often  broken,  when  higher  lands  extend  down  to  the  tide,  and 
the  submarine  plain  is  separated  from  the  subaerial  plain  only 
by  sea  cliffs.  In  this  northern  region  the  land  portion  of  the 
plain  is  very  irregular:  in  some  jtlaces  it  is  naiTow,  in  other 
places  it  expands  to  considerable  width,  but  altogether  it  is 
much  less  conspicuous  than  it  is  below  the  Hudson.  South  of 
Macon,  Ga.,  there  is  an  irregular  line  of  parting  between  tlie 
waters  of  the  Atlantic  and  the  waters  of  the  gi-eat  Gulf.  That 
portion  which  drains  into  the  Atlantic  is  still  called  the  Atlantic 
Plain,  and  it  thus  embraces  a  part  of  Florida  down  to  the  Keys. 
Oft"  southern  Florida  the  submarine  portion  is  greatly  narrowed, 
while  the  marsh  portion  expands  into  the  gi-eat  marshes  of 
Florida,  which  extend  from  the  ocean  to  the  Gidf. 

The  land  plain  is  usually  rich  agricultural  land,  and  is  exten- 
sively cultivated.  The  marsh  plain  has  a  wealth  of  deep  soil, 
and  wherever  redeemed  by  drainage  or  embankments  it  yields 
bountiful  returns  ^to  agi'icultural  laVior.  The  sea  plain  is  the  site 
of  a  coastal  commerce  which  has  already  attained  great  magni- 
tude, and  which  is  steadily  growing.  The  scenery  is  monoto- 
nous in  relief,  but  wonderfully  varied  with  bays  and  gulfs,  and 
broad,  quiet  rivers,  the  banks  of  which  are  diversified  with  stately 
groves.  From  the  palmetto  of  the  South,  to  the  low,  gnarled 
oaks  of  the  North,  there  is  a  i)aiioi'ajua  of  ever-changing  forests. 
At  the  South,  coral  groves  abound,  which  unite  with  sediments 
from  the  land  to  build  fringing  islands.  Northward  from  the 
coral  homes  great  rivers  loaded  with  sediment  supply  sands  that 
iire  deposited  liy  the  currents,  and  by  the  waves  are  built  into 
other  fringing  islands  all  along  the  marine  plain  until  we  reach 
the  great  sand  banks  of  the  North.  In  a  few  places  there  are 
diastrophic  islands,  and  behind  them  there  are  great  harbors,  as 
in  New  York  Bay.  Especially  along  the  coast  of  New  England 
there  are  many  diastrophic  islands,  and  from  New  York  to  Bos- 
ton they  protect  quiet  sounds  that  are  utilized  by  commen-e  in 
great  fleets,  whose  white  sails  skim  the  sounds  all  summer  long. 


7(3  PHYSIOGRAPHIC    REGIONS    OF   THE    UNITED    STATES. 

Aloug  the  coast  of  Maine  the  tides  sometimes  rush  up  the  rivers 
iu  gi-eat  bores,  and  the  rock-bound  coast  is  protected  by  sea  cliflfs. 
On  this  beautiful  Athmtie  coast  the  traveler  may  sail  from  coral 
reefs  to  seas  where  icebergs  float,  and  may  retui'u  by  the  steel 
highway  from  cranberry  gardens  to  orange  gi-oves. 

THE  PIEDMONT  PLATEAUS. 

The  Piedmont  Plateaus  lie  west  and  northwest  of  the  central 
portion  of  the  great  Atlantic  Plains.  The  rocks  of  which  they 
are  composed  are  maiiilj'  of  Aix-hjean  age,  and  are  all  more  or 
less  metamorphic.  Often  they  are  of  slaty  structure;  that  is, 
the  sedimentary  beds  originallj-  laid  down  in  strata  have,  by 
diastrophism,  compression,  and  chemical  change,  become  meta- 
morphosed; ofttimes  the  old  stratified  structure  has  been  de- 
stroyed and  a  new  structure  imposed  upon  the  rocks,  so  that 
they  appear  iu  thin  plates  which  do  not  conform  to  the  old 
stratified  planes.  This  structure,  given  by  metamorphism,  is 
known  as  slaty  structure.  Besides  the  original  sedimentary 
beds,  primarily  there  were  gi-eat  l)odies  of  lavas,  and  these  also 
have  been  metamorphosed.  During  Cretaceoiis  time,  while  the 
Atlantic  plains  to  the  eastward  were  sometimes  land  plains  and 
sometimes  submarine  plains,  and  while  the  coast  line  was  shift- 
ing back  and  forth,  the  Piedmont  region  a^  degi'aded  to  a 
gi'eat  system  of  i)]ains  which  were  traversed  ^^^treams  running 
to  the  sea.  The  whole  plain  seems  not  to  have  been  brought 
down  to  the  level  of  the  sea,  but  to  have  inclined  slightly  to  sea- 
ward aud  toward  the  valleys  of  the  streams;  so  that,  iu  refer- 
ring to  its  plain  condition,  the  region  is  often  called  a  peneplain. 
When  the  land  portions  of  the  Atlantic  Plain  were  finally  un- 
masked by  the  upheaval  of  the  land  aud  the  retreat  of  the  sea, 
the  same  system  of  upheaval  extended  throughout  the  Piedmont 
region,  and  has  continued  with  intermission  to  the  present  time, 
until  the  old  plains  have  now  reached  an  altitude  which  consti- 
tutes them  plateaus,  as  that  term  is  now  (h^fined.  We  have 
already  shown  that  the  Piedmont  region  is  narrowly  defined  on 
the  Atlantic  side  by  the  fall  line,  which  separates  it  from  the 
plains.  On  the  northwestern  side  it  is  bounded  by  the  Appa- 
lachian Mountains.  The  line  of  separation  between  these  two 
regions  is  not  always  as  clearly  defined  as  that  on  the  other  side, 
and  yet  in  the  main  it  is  distinct. 


THE   PIEDMONT    PLATEAUS.  77 

The  region  had  a  great  extension  of  plains,  sometimes  diver- 
sified with  many  hills,  before  its  upheaval  into  the  plateau  condi- 
tion. In  various  places  there  were  areas  of  quartzite  whit-h  were 
hard  and  unyielding  to  degradation,  and  which  remained  as  hills. 
In  other  regions  there  were  bodies  of  firm  granite,  probably  of 
volcanic  origin,  which  also  resisted  degradation  and  remained  as 
hills.  Over  the  old  plain  surface  these  ancient  hills  still  remain 
to  crown  the  plateaus.  As  the  upheaval  began,  the  plain  was 
tilted  eastward,  and  the  sluggish  streams  were  urged  to  greater 
activity,  until  they  became  swiftly  rolling  rivers  and  creeks,  and 
even  the  brooks  danced  in  joy  with  the  new  activity.  Witli 
this  new-born  life  they  began  to  corrade  their  channels  and  to 
cut  them  in  deep  gorges,  and  griidually  they  carved  out  valleys, 
and  divided  the  old  plain  into  plateaus  separated  by  luxuriant 
valleys  with  meandering  stream  channels  and  flood  plains ;  wliile 
the  hills  on  either  side  ascended  to  ancient  plains,  now  plateau 
summits  with  their  embossed  hills.  As  corrasion  pres.ses  hard 
upon  upheaval,  channels  are  cut  more  rapidly  than  the  general 
surface  is  disintegrated  and  washed  away,  and  for  this  reason 
the  lateral  stream  gorges  and  valleys  have  a  slightly  convex 
profile;  but  when' upheaval  ceases,  convex  pi'ofiles  are  slowly 
changed  to  concave  profiles.  By  this  characteristic  geologists 
often  discover  important  time  relations  l)etween  diastrophism 
and  degradation.  From  these  cliaracteristics  of  convexity  and 
concavity,  and  from  certain  related  facts,  it  is  known  that  the 
Piedmont  Plain  was  not  upheaved  evenly  and  simultaneously  in 
all  its  parts,  l)Ut  that  it  was  lifted  now  at  one  place  and  now  at 
another.  Where  first  lifted,  the  gorges  and  valleys  are  convex ; 
where  last  lifted,  they  have  concave  profiles.  There  is  not  space 
here  to  characterize  fully  the  Piedmont  region  in  this  inspect, 
but  reference  will  be  made  to  one  of  the  districts  which  has  been 
uplifted  in  very  late  geologic  times. 

The  Susquehanna  Eiver,  wliich  deboiiches  into  the  head  of 
(Jhesapeake  Bay,  is  well  marked  by  rapids  at  the  fall  line  near 
its  mouth ;  but  above,  swift  waters  continue,  crossing  the  Pied- 
mont Plateaus  uji  into  the  mountain  region.  In  late  geologic 
time,  tide  water  extended  throiigh  tins  reach  of  the  river  in  a 
broad,  shallow  channel  which  carried  fresh  water  fi'om  above. 
By  the  last  upheaval  and  tilting  in  tliis  stretch  from  the  fall 
line  into  the  mountains,  the  flow  of  the  river  was  accelerated, 
and  the  swift  waters  have  mainly  swept  away  sediments  that 


78  PHYSIOGRAPHIC    KEGIONS   OF  THE   UNITED    STATES. 

had  accumulated  on  the  bottom  of  the  channel  and  along  the 
old  flood  plain.  Yet  this  upheaval  was  late,  and  may  be  yet  in 
progress ;  so  that  sufficient  time  has  not  elapsed  to  carve  a  new 
channel  in  the  old  rocks  below,  but  only  enough  to  carry  away 
the  greater  part  of  the  soft  materials, — the  ooze  and  sediments 
that  gather  on  the  bottom  of  the  old  broad-cut  river.  The  old 
bottom  of  hard  rocks  was  very  irregular  as  a  floor;  and  as  the 
soft  rocks  have  been  carried  away,  this  irregular  surface  ap- 
pears. Many  channels  in  the  hard  rocks  have  been  cut,  and 
the  irregularity  is  now  even  greater  than  it  was  originally.  For 
this  reason  the  Susquehanna  falls  into  a  very  broad,  shallow 
channel,  beset  with  gi-eat  bowlders  and  bordering  ledges  of 
rock ;  and  it  often  runs  in  many  channels,  while  patches  of  sedi- 
ments that  lined  the  old  river  bottom  still  remain  here  and 
there.  It  is  thus  that  history  is  recorded  in  river  channels, 
graved  in  ghi)lis  l>y  corradiiig  streams. 

Many  fissures  in  the  metamorphic  rocks  of  the  Piedmont 
Plateaus  have  been  filled  by  the  deposition  of  white  quartz  onc.e 
held  in  solution  in  the  underground  waters.  In  this  manner 
extensive  veins  of  the  white  crystalline  mineral  ramify  through 
the  rocks,  which  are  usually  dark  and  somber,  but  are  enlivened 
with  the  veins  of  crystalline  quartz.  In  these  veins  minute 
fragments  of  gold  are  discovered  throughout  the  Piedmont  re- 
gion. Ever  the  shining  metal  has  attracted  the  eye  of  ciAilized 
man,  and  gold  mining  has  been  extensively  practiced;  but  the 
quantity  found  has  never  been  very  great,  and  usually  the 
quartz  veins  have  failed  to  renumerate  labor. 

THE   APPALACHUN   RANGES. 

These  ranges  extend  from  southern  New  York  into  the  State 
of  Georgia.  On  the  southeast  the  Piedmont  Plateaus  stretch 
from  the  foothills  of  the  mountains.  On  the  northwest  the 
great  Alleghany  Plateaus  lie,  joining  the  Lake  Plains  in  the  re- 
gion of  the  Gre;at  Lakes,  and  the  Prairie  Plains  in  the  region  of 
Ohio  River.  These  mountain  ranges  are  composed  mainly  of 
ridges  whose  longitudinal  direction  is  from  the  northeast  to  the 
southwest.  Between  these  ridges  valleys  are  found.  Usually  a 
valley  separates  the  mountain  region  from  the  Alleghany  Pla- 
teaus. This  system  of  mountains  is  naturally  divided  into  two 
parts,   the    northern   Appalachian   and   southern   Appalachian 


THE   APPALACHIAN    RANGES.  79 

ranges.  On  the  north  the  streams  heading  in  the  Alleghany 
Plateaus  run  southeastward  into  the  Atlantic  Ocean,  and  cut 
through  the  ranges  by  great  gorges  that  are  popularly  called 
■water  gaps;  but  south  of  New  River  the  Appalachian  Ranges  are 
drained  into  the  Gulf.  The  streams  head  in  the  crest  of  the  most 
eastern  rauge,  and  cut  through  the  ranges  to  the  west  by  flariug 
gorges,  and  most  of  them  empty  into  Ohio  River  by  the  waters 
of  Cumberland  and  Tennessee  rivers.  In  early  Cretaceous  and 
Juratrias  time  the  Appalachian  Mountain  and  the  Alleghany 
Plateau  regions  were  reduced  nearly  to  a  base-level.  In  Creta- 
ceous time  these  regions  were  again  lifted  ])y  diastrophic  agen- 
cies. The  northern  plateaus  were  tilted  in  a  manner  which 
turned  their  waters  toward  the  Atlantic,  while  the  southern 
plateaus  were  lifted  in  such  a  manner  that  their  waters  were 
turned  toward  the  Ohio ;  so  that  now  we  find  the  Delawai'e,  the 
Susquehanna,  and  the  Potomac  rising  far  to  the  northwest  in 
the  Alleghany  Plateaus,  and  flowing  southeast  across  the  Appa- 
lachian Ranges  to  the  Atlantic,  wliile  New  River  and  the  tril)u- 
taries  of  the  Tennessee  rise  far  to  the  southeast  in  the  Blue 
Ridge,  and  flow  northwest  across  the  Appalachian  Ranges  and 
the  plateaus  beyond  to  the  Ohio.  The  two  portions  were  further 
differentiated  by  reason  of  a  gi'eat  distinction  between  the  meth- 
ods of  interior  diastropliism.  The  folding  of  the  northei'n  Apjia- 
lachian  Mountain  belt  was  more  regular  in  great  anticlinal  and 
synclinal  flexures,  while  in  the  upheaval  of  the  southern  moun- 
tains the  folds  were  crowded  together  and  often  faulted  on  a 
gigantic  scale.  These  ancient  folds  were  planed  down  wlu>n  the 
whole  region  was  lirought  nearly  to  a  l)ase-levcl,  and  the  new  val- 
leys cut  on  the  later  upheaval  were  carved  mainly  in  soft  rocks, 
while  the  mountains  that  are  left  are  composed  mainly  of  hard 
rocks.  The  valleys,  therefore,  do  not  follow  downturned  flexures, 
but  lie  along  out-cropping  edges  of  hard  beds,  while  the  streams 
themselves  from  time  to  time  cut  through  the  ranges  by  flaring 
gaps.  In  the  same  manner  in  the  southern  mountains,  hard  rocks 
make  mountains,  and  soft  rocks  produce  valleys;  but  these  val- 
leys ai'e  less  regular  below,  because  of  the  great  lateral  thrusts  by 
which  the  strata  were  closely  plicated  and  often  faulted.  TTsually 
the  valley  between  the  mountains  and  the  Alleghany  Plateaus  is 
wider,  and  is  a  more  conspicuous  feature,  than  the  other  inter- 
range  valleys.  The  ridges  themselves  are  rather  monotonous 
mountains,  but  in  the  water  gaps  picturesque  -sceneiy  is  found. 


80  PHYSIOGR.\PHIC    REGIONS    OF    THE    UNITED    STATES. 

The  valleys  that  are  regular  and  beautiful  are  highly  cultivated 
and  densely  populated. 

.AXLEGHANY   PLATEAUS. 

In  a  broad  way  these  jilateaus  are  carved  out  of  a  great  block 
of  sedimentary  rock  tilted  to  the  northwest  from  the  Appa- 
lachian Mountains  down  to  the  Prairie  and  Lake  plains.  In 
Cretaceous  and  Juratrias  time  the  block  was  graded  to  a  plain, 
the  surface  of  which  generally  conformed  to  the  stratification. 
The  gi'eat  block  is  slightly  warped,  and  there  are  many  local  evi- 
dences of  minor  diastrophism.  In  general  the  plateaus  are 
crossed  by  deep,  comparatively  narrow  water  channels.  As  the 
streams  run  in  deep  channels,  all  the  larger  ones  being  in  gorges 
from  two  hundi'ed  to  a  thousand  feet  in  depth,  the  dissection  of 
the  plateau  block  is  often  miniite,  and  many  plateaus  are  thus 
formed.  The  region  of  the  Piedmont  Plateaus,  Appalachian 
Mountains,  and  Alleghany  Plateaus,  in  its  earlier  geologic  his- 
tory, extended  farther  to  the  northeast,  and  gradually  faded  out ; 
but  its  structure  is  still  preserved,  though  more  or  less  masked 
by  glaciation.  It  is  even  to  be  observed  in  the  Green  Mountains 
of  Vermont,  as  well  as  in  the  Berkshire  Hills  of  Massachusetts, 
which  constitute  a  part  of  the  Green  Mountains.  But  north  of 
the  Piedmont  Plateaus  the  region  has  been  carved  by  glaciation 
and  masked  by  glacial  hills,  so  that  it  is  best  described  by  itself. 

NEW   ENGLAND   PLATEAUS. 

In  this  and  the  two  preceding  monographs  mention  has  been 
made  of  the  action  of  glaciers  in  grading  the  land,  but  the  sub- 
ject did  not  receive  adequate  treatment  for  want  of  space.  Yet 
in  characterizing  the  physiogi-aphic  regions  of  the  United  States 
it  becomes  necessary  to  say  something  more  of  the  action  of  ice, 
and  of  the  history  of  a  time  known  as  the  glacial  period. 

The  most  of  Greenland  is  now  covered  by  ice.  Ice  is  found 
over  great  areas  of  the  northern  extremity  of  this  continent  and 
far  down  the  Pacific  coast.  At  different  times  in  the  Pleistocene 
period  this  ice  capping  of  the  land  reached  much  farther  south- 
ward. There  was  one  great  body  of  ice,  known  as  the  Lauren- 
tide  Glacier,  which  extended  over  Canada  and  other  parts  of 
British  America  down  into  the  United  States,  its  most  extreme 


NEW   ENGLAND   PLATEAUS.  81 

lobe  reaching  to  a  point  in  the  Mississippi  Valley  not  far  from 
the  mouth  of  the  Ohio.  Geologists  have  shown  that  it  covered 
an  area  of  about  three  milliou  square  miles.  There  were  other 
great  glaciers  farther  west  which  we  need  not  here  consider. 

The  Laureutide  Glacier  endured  for  a  long  time,  and  passed 
through  many  phases  of  history.  Perhaps  it  existed  at  two 
or  three  different  times,  with  intervening  periods  of  milder 
climate,  when  it  was  melted.  In  its  greatest  development  it 
must  have  accumulated  to  a  thickness  of  hundreds  or  thousands 
of  feet.  Its  different  portions  were  ever  moving  on  the  surface 
of  the  land,  and  grinding  up  the  rocks  below,  and  pushing  them 
down  the  slopes  in  a  general  way  to  the  southward,  with  many 
variations.  The  rains  fell  upon  this  glacier  through  the  centu- 
ries, and  the  sun  melted  the  ice,  and  the  water  percolated  to  the 
surface  of  the  ground,  and  flowed  away  in  subglacial  streams 
that  carried  with  them  the  rock-flour  gi-ound  by  the  ice,  which 
was  armed  with  rocks  carried  along  by  tlie  ice.  It  is  thus  that 
the  great  glacier  served  as  a  mighty  agenciy  for  the  degradation 
of  the  land,  pushing  the  bowlders  and  ground  material  along  its 
bottom,  and  carrying  it  away  in  channels,  often  piling  it  up  in 
moraines,  drumlins,  kames,  eskars,  and  other  forms,  and  spread- 
ing the  finer  materials  in  great  sheets  of  clay  and  fine  sand. 

A  portion  of  the  Laureutide  Glacier  was  expanded  over  New 
England  and  New  York  down  to  the  very  site  of  the  great  city. 
Over  this  region  it  extended  for  a  long  time,  though  its  existence 
may  have  been  intermittent;  but  it  remained  long  enough  to 
accumulate  masses  of  ice  with  power  to  perform  the  stup«>ndous 
task  of  refashioning  the  surface  of  the  land.  It  found  mountains, 
plateaus,  plains,  valleys,  and  hills,  but  it  changed  them  all  by 
carving  new  forms  to  its  own  liking ;  but,  more  than  all,  it  bi;ilt  a 
vast  army  of  hills,  and  filled  many  valleys.  The  modified  moun- 
tains yet  remain ;  the  old  plateaus,  though  changed,  still  stand ; 
but  the  valleys  and  hills  are  to  a  large  extent  new  features.  I 
have  called  this  region  the  New  England  Plateaus  ])ecause  before 
tlie  advent  of  the  ice  it  was  a  great  group  of  plateaus  diversified 
with  mountains,  hills,  and  vallej^s.  Now  new  hills  are  found 
widely  scattered  over  it,  sometimes  in  its  valleys,  always  over  its 
plateaus  and  over  the  flaidvs  of  its  mountains.  The  Adirondacks 
still  stand,  much  modified  by  glaciation.  Down  Vermont  the 
Green  Mountains  extend  into  the  State  of  Massachusetts,  where 
they  are  called  the  Berkshire  Hills.     Everywhere  they  have  been 


82  PHYSIOGEAPHIC    REGIONS   OF   THE   UNITED   STATES. 

remodeled  by  ice.  Still  to  the  east,  in  New  Hampshire,  are  the 
White  Mouutains,  with  Mouut  Washiugtoii  as  a  culminating 
peak ;  and  there  are  loue  raouutaius  scattered  over  Maine,  and 
the  region  extends  beyond  our  boundary  into  British  territory. 
The  structure  of  these  plateaus  is  more  or  less  masked  by 
glacial  hills,  and  there  are  great  valleys  with  river  plains  exhibit- 
ing fragments  of  ancient  glacial  hills.  Near  the  Atlantic  the 
coastal  plain  is  broken,  and  many  sea  cliffs  ai-e  found,  and  the 
coastal  marshes  are  very  irregular.  In  New  York,  glacial  valleys 
and  more  recently  cut  river  valleys  are  found,  and  limited  plains 
are  seen,  especially  in  the  region  of  the  Finger  Lakes.  Scattered 
through  the  region  are  many  lakes  of  clear,  cold,  beautiful 
waters ;  and  there  are  many  marshes,  some  fed  by  the  tide  with 
salt  water,  but  many  more  with  fresh  water;  and  the  interior 
lakes  are  mainly  of  glacial  origin. 

LAKE  PIAINS. 

In  the  northern  portion  of  the  United  States  there  is  a  lake 
region  which  extends  still  northward  far  into  British  America. 
In  the  midst  of  the  region  lie  the  Great  Lakes,  —  Ontario,  Erie, 
Huron,  Michigan,  and  Superior;  and  about  them,  to  north, 
south,  east,  and  west,  many  others  are  found  of  less  magnitude, 
to  the  number  of  thousands.  The  region  is  in  large  part  drained 
by  the  St.  Lawrence,  and  in  small  part  by  the  Mississippi.  The 
Great  Lakes  are  primarily  of  diastrophic  origin,  but  they  have 
all  been  remodeled  by  ice,  while  the  smaller  lakes  are  due  mainly 
to  glaciatiou.  The  gi-eat  Laurentide  Glacier  extended  over  all 
this  region,  and  buried  it  deeply  under  the  ice,  and  during  its 
history  made  gi-eat  changes  in  the  land  surface  by  degrading  old 
forms,  and  building  new  lands. 

Previous  to  the  advent  of  the  glacial  age,  the  region  was  in 
the  main  a  system  of  great  plains,  with  hills  and  some  minor 
plateaus ;  but  when  the  ice  came,  it  covered  them  all,  and  wrought 
a  regeneration,  leaving  the  Great  Lakes  still  lying  in  their  dias- 
trophic basins,  but  adding  to  the  region  a  vast  assemblage  of 
glacial  lakes,  many  of  which  remain,  while  many  have  been  filled 
with  peat,  and  drained  by  new  stream  channels.  The  plains  left 
by  the  glacier  were  low,  with  comparatively  little  relief. 

Since  the  disappearance  of  the  ice  sheet,  diastrophism  has 
progressed  as  of  old;  so  that  the  Lake  Plains  have  been  warped, 


PKAIKIE  PLAINS.  83 

and  it  becomes  easy  to  identify  these  diastropliic  changes.  As 
it  is  a  region  of  many  lakes,  and  as  the  streams  liave  all  been 
corrading  new  channels  since  the  disappearance  of  the  ice,  the 
great  and  small  lakes  have  often  been  terraced.  The  greater 
plains  have  in  this  manner  been  cut  into  small  lake  plains  that, 
are  low  stairways  from  shores  to  high  lands.  Thus  the  region 
is  characterized  by  great  plains  base-leveled  in  earlier  geologic 
periods,  releveled  during  the  glacial  period,  and  terraced  with 
lake  plains  since  that  time.  By  reason  of  its  many  lakes  and  its 
numerous  terraces,  it  is  well  characterized  as  the  region  of  Lake 
Plains.    Four  districts  may  be  recognized,  as  shown  on  the  map. 

PRAIRIE   PLAINS. 

On  the  south  and  on  the  west  of  the  Lake  Plains  stretch  the 
great  Prairie  Plains.  When  this  region  was  first  visited  by 
white  men,  much  of  it  was  destitute  of  forests.  In  the  east, 
glades  and  small  prairies  existed ;  farther  westward  the  prairies 
became  larger,  until,  in  eastern  Indiana,  the  prairie  region  pre- 
vailed in  extent  over  the  forest  region,  while  beyond  the  Missis- 
sippi the  prairies  were  interrupted  only  l)y  the  groves  that 
border  the  streams.  This  pniirio  region  sweei)S  around  the  great 
Ozai'k  Hills,  and  extends  southwai'd  nearly  to  the  Rio  Grande 
del  Norte.  Here  and  there  it  is  relieved  by  low  hills,  and  it  is 
cut  with  a  labyrinth  of  stream  channels,  on  the  borders  of  which 
flood  plains  appear  that  were  usually  covered  with  trees  in  the 
olden  time.  The  Laurentide  Glacier  extended  across  this  prairie 
region  down  nearly  to  the  mouth  of  the  Ohio;  and  wherever  it 
was  spread,  great  glacial  accumulations  apjx^ar  as  beds  of  clay, 
sand,  and  gravel,  and  sometimes  as  glacial  hills.  On  the  last 
reti'eat  of  the  ice  there  were  left  behind  many  little  b;isins,  into 
which  the  waters  were  gathered;  and  a  multitude  of  little  lakes 
were  thus  formed,  many  of  which  were  gi-adually  drained  by  the 
streams,  and  filled  with  peat.  It  is  thus  a  region  of  small  extinct 
lakes,  whose  shores  Avere  rarely  terraced  because  of  the  l)rief  life 
awarded  to  these  little  bodies  of  water. 

On  the  west  the  prairies  merge  imperceptibly  into  the  region 
popularly  known  as  the  "  Great  Plains,"  but  which  we  now  call  the 
Great  Plateaus,  for  the  reason  hereafter  to  ajipc^ar. 

The  lands  of  the  prairies  are  fertile.  Douglas  Jerrold  said, 
that,  if  you  tickle  them  with  a  plow,  they  will  laugh  with  a  liar- 


■84  PHYSIOGRAI'HIC    REGIONS   OF   THE   UNITED    STATES. 

vest.  When  the  couutiy  was  first  settled,  the  districts  far  away 
from  standing  timber  were  supposed  to  be  almost  uninhabitable 
for  the  want  of  fuel  and  timber ;  but  under  the  prairies  vast  coal 
fields  have  been  foimd,  and  the  men  of  the  prairies  have  learned 
to  fence  with  hedges  and  iron  wires,  and  they  have  built  railroads, 
on  which  they  have  carried  the  lumber  necessary  for  their  homes. 
The  agricultural  industries  of  all  that  land  have  flourished. 
Gradually  the  lowlands  have  been  drained  and  tilled  and  the 
higher  lands  have  been  plowed,  forest  groves  have  been  planted 
and  the  old  woods  have  spread,  thousands  of  orchards  have  been 
gi'own  and  vineyards  have  been  jilanted  and  gardens  cultivated, 
until  a  greater  proportion  of  the  land  has  been  brought  under 
the  plow  than  that  of  any  other  region  of  the  world  of  the  same 
magnitude.  Two  districts  are  shown  on  the  map, — the  one 
glaciated,  and  the  other  not. 

THE   GULF   PLAINS. 

On  either  side  of  the  Mississippi  Eiver,  from  a  little  above 
the  mouth  of  the  Ohio,  a  great  plain  stretches  to  the  south, 
and  expands  to  the  Gulf  waters.  On  the  east  the  border  of 
this  plain  skirts  the  Alleghany  Plateau  and  the  point  of  the 
Piedmont  Plateau,  and  extends  east  to  the  line  of  parting 
waters  between  the  Atlantic  and  Gulf  drainage,  which  it  follows 
into  the  marshes  of  lower  Florida.  On  the  west  it  flanks  the  foot 
of  the  Ozark  Mountains,  and  continues  southwest  ward  to  the  Rio 
Grande  del  Norte.  iVll  of  this  area  we  call  the  Gulf  Plains.  Down 
its  middle  the  Mississippi  runs,  and  along  the  Mississippi  and  up 
its  important  trilnitaries  there  is  a  great  flood  plain.  Thus  the 
Gulf  Plains  are  divided  into  five  gi'eat  districts, — the  East  Gulf 
Plain,  iho  West  Gulf  Plain,  the  Flood  Plain  of  the  Mississippi,  the 
Coastal  Marshes  flooded  by  salt  water  from  the  Gulf  itself  and 
by  fresh  water  from  the  land,  and  the  Submerged  Plains  extend- 
ing into  the  Gulf,  so  that  there  is  a  submarine  portion,  as  on  the 
Atlantic  coast.  Under  the  waters  of  the  Gulf,  far  out  at  sea,  the 
submarine  plain  is  ended  by  a  comparatively  abrupt  declivity, 
where  the  Gulf  bottom  drops  off  from  shallow  into  deep  waters. 

The  Mississi]ipi  Flood  Plain  starts  at  tlie  foot  of  the  great 
glacial  deposits  in  Illinois,  and  at  the  Gulf  end  it  expands  into 
a  great  delta  built  into  the  Gulf  by  sediments  brought  down  by 
the  mighty  river.    This  flood  plain  is  usually  well  marked  around 


THE    OZARK   MOUNTAINS,  85 

its  outlines  by  high  bluffs  of  loess.  During  glacial  time  the  Gulf 
coastal  plain  seems  to  have  been  somewhat  more  depressed  than 
at  present,  and  the  water  of  the  glacier  gathered  into  g,  great 
basin  which  emptied  into  the  Gulf.  In  this  basin  the  rock-flour 
gi'ound  by  the  mealing  stones  of  vast  glaciers  was  deposited  as 
an  exceedingly  fine  sediment.  When  the  Laurentide  Glacier  was 
melting  away  into  fragments  in  the  far  north,  the  laud  rose 
again  a  little,  and  the  Mississippi  cut  for  itself  a  new  channel, 
which  was  widened  into  a  flood  plain.  The  material  into  which 
the  channel  and  the  flood  plain  were  cut  was  of  glacial  origin, 
and  we  call  it  loess;  and  thus  the  bluffs  are  of  this  formation. 
The  Gulf  region  is  rich  with  fields  of  corn,  tobacco,  and  cotton. 

In  pre-Columbian  times  the  entire  region  was  a  primeval  for- 
est of  giant  trees  and  dense  undergrowth  entangled  with  vines. 
Into  these  forests  aboriginal  tribes  penetrated  to  fish  in  the 
waters,  to  hunt  on  the  land,  and  to  cultivate  little  garden  patches 
in  corn  and  squashes.  Here  they  built  mounds  on  which  their 
homes  were  erected;  here  they  buried  their  dead  in  mortuary 
mounds;  and  here  they  constructed  great  tumuli  upon  whicli 
stood  their  council  chambers,  and  where  their  ceremonies  were 
held.  On  these  artificial  hills  they  established  their  tribal  homes ; 
worshiped  the  sun,  moon,  and  stars,  and  nuuiy  animals ;  organ- 
ized tribal  governments  of  elaborate  structure;  and  enforced 
laws  that  secured  a  high  state  of  justice. 

THE   OZARIC    MOUNTAINS. 

Extending  southward  and  westward  from  the  Iron  Moun- 
tains of  Missouri  far  into  Arkansas,  there  is  an  elevation  of  laud 
which  we  call  the  Ozark  Mountains  or  Ozark  region.  This  re- 
gion has  an  interesting  though  complex  history.  It  is  projierly 
divided  into  two  districts.  That  north  of  Arkansas  River  has 
been  a  great  plateau,  and  still  retains  many  of  the  features  of  a 
plateau,  but  it  is  deeply  trenched  by  numerous  winding  and 
complicated  streams;  and  the  reliefs  or  elevations  whidi  have 
been  preserved  have  the  structure  of  huge  hills  and  small  moun- 
tains, though  a  few  of  the  forms  are  of  more  gigantic  structure. 
Some  of  the  greater  elevations  above  the  streains  are  in  the  Iron 
Mountain  region,  and  others  are  called  the  Boston  IMountains. 
The  rocks  are  sometimes  faulted,  and  the  streams  often  follow 
fault  lines.    In  the  Boston  Mountains  the  strata  are  chiefly  hori- 


86  PHYSIOGRAPHIC    EEGIONS    OF   THE    UNITED    STATES. 

zontal,  and  are  deeply  chauueled.  On  the  south  the  rocks  of  this 
region  in  a  general  way  bend  down  in  a  synclinal  fold,  and  re- 
appear south  of  the  river;  below  they  are  found  strongly  folded 
and  sometimes  faulted,  and  are  eroded  into  long,  i:)arallel  moun- 
tain ridges  with  intervening  valleys.  Going  southward,  the 
ridges  have  a  general  east-and-west  trend,  but  are  often  curi- 
ously carved  and  faulted.  In  the  most  southern  portion  of  the 
region  the  streams  are  transverse  to  the  rock  structure.  It 
would  be  well  to  call  the  northern  district  the  Ozark  Plateaus, 
and  the  southern  district  the  Ozark  Eanges. 

THE    GREAT    PLAINS    (PLATEAUS). 

The  region  popularly  known  as  the  "  Great  Plains  "  is  in  fact 
a  gi'eat  group  of  elevated  plateaus.  They  have  therefore  been 
colored  as  plateaus,  and  grouped  in  districts  which  are  called 
plateaus.  It  would  serve  to  harmonize  the  nomenclature  if  the 
name  could  be  changed  from 2)I(ih/s  io  jilateaKS.  The  zone  in  the 
United  States  extends  from  British  America  to  the  Rio  Grande ; 
and  the  region  extends  far  northwai'd  in  British  America,  and 
southward  in  the  Republic  of  Mexico.  Within  the  United  States 
four  districts  are  demarcated. 

The  Missouri  district  is  deeply  trenched  by  the  upper  Missis- 
sippi River  and  its  great  tributaries,  in  such  a  manner  that  the 
blocks  to  the  north  have  their  long  axis  extending  from  the 
northwest  to  the  southeast,  while  the  plateaus  south  of  the  river 
have  their  long  axis  extending  from  the  southwest  to  the  north- 
east. The  principal  streams  of  the  region  have  their  sources  in 
the  Stony  Mountains,  and  eaiTy  large  volumes  of  water,  while 
the  local  tributaries  ai"e  small.  Along  many  of  the  smaller 
streams  there  are  extensive  areas  minutely  dissected  by  storm- 
water  streams.  Tbe  rocks  ai'e  maiidy  soft  shales,  so  that  corra- 
sion  is  rapid ;  and  the  hills  thus  formed  in  the  easily  carved  shales 
are  naked  and  desolate,  and  hence  are  called  had  Icnicls. 

In  the  district  to  the  south,  called  the  Platte  Plateaus,  the 
rivers  flow  mainly  in  an  easterly  direction ;  and  the  trenches 
whicli  they  fomi  divide  the  country  into  long  ta])le-linids  having 
the  same  direction.  The  ti-enehes  are  wider  and  shallower  than 
in  the  north.     The  streams  all  join  the  Mississippi. 

Going  to  the  soutliward,  the  Arkansas  Plateaus  are  found. 
The  Arkansas,  the  Cimarron,  and  the  two  forks  of  Canadian 


THK   STONY   MOUNTAINS.  87 

River,  drain  the  entire  district,  and  separate  it  into  long  east- 
and-west  plateaus.  The  trenches  of  the  rivers  are  not  very  deep, 
but  are  usually  very  wide,  and  their  summits  are  gi'eat  treeless 
plains.    All  these  rivers  join  the  Mississippi  soutli  of  the  Ohio. 

The  fourth  district  is  drained  mainly  by  the  Pecos,  having  a 
southerly  direction ;  but  its  eastern  margin  is  drained  by  tribu- 
taries of  Bed,  Brazos,  Nueces,  and  Colorado  rivers  of  Texas.  This 
is  the  Staked  Plains,  the  region  best  adapted  to  the  study  of  the 
four  great  laws  of  corrasion,  which  may  he  stated  as  follows :  — 

First,  other  things  being  equal,  tlie  rate  of  corrasion  pro- 
gressively increases  with  the  increase  of  the  load  Avhicli  is  the  in- 
strument of  corrasion ;  second,  other  things  being  equal,  vertical 
corrasion  directly  increases  with  the  declivity  of  the  stream; 
thh~d,  other  things  being  equal,  lateral  corrasion  increases  in- 
versely with  the  declivity  of  the  stream,  and  vertical  cori'asion 
is  transmuted  into  lateral  corrasion;  J'omili, luaxiuaun  corrasion 
is  produced  by  maximum  volume  of  water,  maximum  load,  and 
minimum  declivity,  and  the  corrasion  is  lateral ;  Jiftli,  a  stream 
heading  in  mountains,  and  crossing  arid  lands,  is  supplied  with 
a  great  amount  of  sediment  by  frequent  winds  and  occasional  hard 
rains,  and  is  caused  to  spread  in  a  wide  channel,  so  that  the  depth 
of  water  is  greatly  diminished,  while  the  sand,  having  but  a  short 
distance  to  fall,  is  driven  along  by  short  excursions :  so  that  the 
rate  of  corrasion  diminishes  in  inverse  proportion  to  the  depth 
of  the  stream. 

THE   STONY   MOUNTAINS. 

The  Stony  Mountains  constitute  a  well-marked  gi'oup  drained 
by  the  head  waters  of  the  Missouri  on  the  east,  and  the  head 
waters  of  Snake  and  Columbia  rivers  on  the  west.  The  name 
"  Stony  Mountains"  was  first  given  to  this  group,  but  was  after- 
ward clianged  to  "  Rocky  Mountains,"  and  then  exti'uded  indefi- 
nitely over  other  groui)s ;  l)ut,  as  the  group  must  be  distinguished 
from  others  for  physiograpiiic  purposes,  it  seems  well  to  return 
to  the  original  designation.  Theses  mountains  appear  to  be  of 
very  diverse  structure.  There  are  a  number  of  great  ranges; 
but  they  are  not  very  systematically  grouped,  nnd  have  dift'erent 
directions  because  they  are  complicated  with  vulcanic  moun- 
tains, plateaus,  and  hills.  Some  are  carved  out  of  broad  anti- 
clinal folds,  others  are  greatly  faulted,  and  often  sharp  ridges 


88  PHYSIOGRAPHIC    REGIONS    OF    THE    UNITED    STATES. 

appear;  but  the  geologic  history  of  the  country  has  uot  beeu  so 
fully  worked  out  that  a  eousisteut  story  of  it  can  be  given.  The 
ranges  are  moderately  high ;  and,  by  reason  of  the  northern  alti- 
tude and  a  fair  amount  of  rainfall,  they  are  covered  for  many 
mouths  •with  snow,  aud  here  many  beautiful  streams  have  their 
origin.  The  flanks  of  the  mouutains  aud  high  plateaus  are  often 
covered  with  great  forests,  and  the  low  foothills  with  gnarled 
trees.  The  valleys  are  rich  and  productive,  though  mainly  tree- 
less. Great  mining  industries  are  prosecuted,  especially  of  gold 
and  silver.  In  the  heart  of  the  gi-oup  are  the  geysers  and  hot 
springs  of  the  National  Park,  which  has  become  a  region  of 
world-wide  resort  because  of  its  wonders  and  its  beauty. 

THE   TAKK   5I0UNTAINS. 

In  southern  Wyoming,  central  Colorado,  and  northern  New 
Mexico  a  great  group  of  mouutains  is  found,  whose  lofty  peaks 
are  characterized  by  a  wilderness  of  crags.  The  ranges  are  more 
irregular  than  those  of  the  Stony  Mouutains,  and  have  a  general 
north-and-south  trend.  Between  the  ranges  there  are  great 
valleys,  which  are  known  as  j)arJx-s.  The  four  most  important 
are  the  North,  Middle,  South,  and  San  Luis  parks;  but  there 
are  others  which  almost  vie  with  them  in  extent,  and  a  gi'eat 
number  of  still  smaller  valleys,  all  of  which  are  alike  called 
parks.  Above  the  timljcr  line  the  peaks  are  naked ;  below,  on 
the  flanks  of  the  mountains,  great  forests  stand,  aud  often  spread 
over  elevated  plateaus ;  while  the  valleys  are  beautiful  prairies 
or  parks.  The  ranges  having  a  north-and-south  direction  are 
carved  out  of  great  anticlinal  folds,  but  in  each  fold  a  zone  of 
maximum  curve  is  usually  discovered  on  either  flank ;  so  that 
the  rocks  at  the  flanks  of  the  ranges  are  abruptly  turned  down, 
and  extend  under  the  parks,  and  are  again  tiirned  abruptly 
above  to  a  nearly  horizontal  jjositiou.  Only  fragments  of  these 
more  horizontal  beds  above  have  been  left :  most  of  them  have 
been  degraded  awaj'.  The  central  portions  of  the  ranges  are  in 
the  main  composed  of  metamorphic  rocks  of  great  age.  This 
more  irregular  structure  is  modified  to  some  extent  by  faults 
and  various  minor  wriid^le?:.  On  the  flanks  of  the  mountains 
and  out  in  the  parks  there  are  many  beds  of  vulcanic  rocks, 
which  serve  still  further  to  modify  the  aspect  of  the  ranges.  In 
a  few  cases,  especially  on  the  western  side,  these  vulcanic  beds 


COLUMBIA    PLATEAUS.  89 

have  been  piled  up  in  mountain  forms.  On  the  eastern  side 
there  are  a  few  outlying  peaks  of  volcanic  origin.  Notable 
among  these  are  the  Spanish  Peaks.  The  gi-oup  terminates  to 
the  south  in  the  neighborhood  of  Santa  Fe.  The  head  waters  of 
Platte,  Arkansas,  and  Canadian  rivers  drain  the  mountains  on 
the  east;  to  the  west  they  are  di-ained  by  the  head  waters  of 
Colorado  River,  which  empties  into  the  Gulf  of  California ;  while 
to  the  south  they  are  di-ained  by  the  Rio  Grande  del  Norte. 
This  is  a  land  of  ranges  and  valleys,  of  peaks  and  parks,  of 
naked  crags,  forest-clad  mountains,  and  plateaus. 

There  are  features  extending  along  the  entire  length  of  the 
gi'oup  from  north  to  soiitli  on  the  eastern  side,  and  again  irreg- 
ularly on  the  western  side,  that  give  rise  to  many  small  and  pic- 
turesque parks  sometimes  called  gardens.  It  has  already  been 
explained  that  the  rocks  of  later  age  are  turned  up  sharply  on 
the  flanks  of  the  mountains  as  sandstones,  shakis,  and  lime- 
stones of  many  colors,  often  of  bright-red  hues,  while  beds  of 
alabaster  are  found.  The  rocks  stand  on  edge.  The  softer  beds 
are  worn  out,  and  the  harder  beds  remain  standing  as  great 
walls ;  so  that  many  beautiful  garden  valleys  are  produced,  par- 
allel to  the  gi-eat  ranges,  and  separating  them  from  the  plains 
below.  The  forms  of  these  rocks  are  often  varied  and  majestic, 
and  sometimes  fantastic.  The  Garden  of  the  Gods,  near  Pike's 
Peak,  is  one  of  these  valleys,  which  has  become  a  favorite  visit- 
ing place  from  the  adjoining  summer  resorts. 

COLUMBU   PLATEAUS. 

To  the  west  of  the  Stony  Mountains  stretches  a  great  plateau 
region  which  is  di'ained  into  the  Pacific  by  tributaries  of  Colum- 
bia River.  It  is  a  complex  of  plateaus  of  diastrophic  and  vul- 
canic origin,  relieved  by  a  few  great  mountains,  and  having 
many  beautiful  valleys.  The  highlands  are  covered  with  for- 
ests; the  lowlands  are  naked. 

In  Cretaceous  time  the  region  had  many  extensive  plains, 
broad  valleys,  high  mountains,  and  some  portions  were  covered 
by  the  sea.  The  mountains  were  mainly  of  granite,  quartzite, 
and  mica  schist,  with  rocks  of  later  age  on  their  flanks. 

In  Eocene  time  extensive  diastrophism  prevailed,  and  with  it 
came  vulcanic  activity,  by  which  a  number  of  great  mountain 
cones  were  erected. 


90  PHYSIOGKAPHIC    llEGIONS    OF   THE    UNITED    STATES. 

Ill  Neooeue  time  the  lavas  were  more  fluid,  and  broke  out  in 
many  new  places,  pouring  out  thin  coulees,  frequently  filling  or 
obstructing  valleys.  These  later  eruptions  continued  for  a  long 
time,  upbuilding  the  region  by  burying  the  old  topogi-aphy  and 
piling  the  lavas  against  the  mountains.  In  the  process,  valleys 
were  often  dammed  by  floods  of  cooling  lavas,  and  behind  these 
obstructions  many  lakes  were  formed.  Since  vulcanism  has 
ceased,  many  of  these  lakes  have  l)een  drained,  and  the  old  lake 
beds  are  now  rich  agricultural  lands.  In  many  places  the  ancient 
mountain  summits  yet  appear,  but  about  them  are  scattered 
great  irregular  vulcanic  jilateaus.  Small  valleys  have  sometimes 
been  carved,  but  often  the  streams  have  cut  narrow  trenches 
which  are  canyons.  Frequently  the  canyon  walls  are  composed 
of  lavas,  sometimes  with  interbedded  lake  beds.  In  the  old 
mountain  regions  gold  and  silver  ai'e  mined,  and  in  many  places 
the  gi'avels  left  in  the  valleys  and  canyons  below  have  much 
gold  in  nuggets,  flakes,  and  dust,  which  gives  rise  to  placer  min- 
ing. Snake  Elver  runs  for  several  hundreds  of  miles  of  its 
course  through  a  canyon  carved  in  the  lavas.  The  walls  of 
the  canyon  are  often  precipitous,  effectually  barring  cross-river 
transit.  In  places  late  coulees  have  dammed  the  river ;  Shoshone 
Falls  are  formed  in  this  manner.  Here  a  mad  torrent  of  water 
plunges  over  a  gi-eat  lava  dam  in  a  cataract  of  gi'andeur. 

COLORADO  PLATEAUS. 

During  the  Cretaceous  period  a  shallow  sea  spread  over  the 
region  of  the  Colorado  Plateaus.  This  great  enibayment  of  the 
ocean  stretched  far  to  the  east,  northeast,  and  southeast,  and  its 
oriental  margin  was  a  little  east  of  where  the  Mississippi  River 
now  runs.  In  the  midst  of  this  sea  there  was  a  great  archipel- 
ago where  now  the  Park  Mountains  stand.  In  late  Cretaceous 
and  early  Eocene  time  the  entire  sea  was  slowly  upheaved,  and 
the  waters  retreated.  The  upheaval  was  very  irregular,  and 
gi'eat  diastfoiihic  basins  were  formed,  in  which  the  fivsh  waters 
accumulated,  and  it  thus  became  a  gi'eat  lake  region.  For  a 
long  time  the  waters  were  brackish,  as  the  lakes  evaporated  to 
such  an  extent  that  only  small  channels  were  cut,  such  being 
sufficient  to  bear  away  the  wat(>r  not  evaporated.  In  a  broad 
way  the  upheaval  in  the  eastern  region  was  by  gentle  flexures ; 
in  the  western  region  it  was  chiefly  by  faults.    As  the  fresh- 


COLOKADO    PLATEAUS.  91 

water  basins  were  many  and  large,  and  the  land  areas  compar- 
atively small,  the  dry  lands  were  washed  down  into  the  Great 
Lakes ;  but  elevation  proceeded  faster  than  degi-adation,  and  the 
lands  grew  both  by  upheaval  and  by  the  enlargement  of  their 
borders  through  deposition,  or,  as  it  is  sometimes  called,  aggra- 
dation. The  slow  ui^heaval  continued  through  Eocene  time. 
Tlie  western  half  became  highly  differentiated  from  the  eastern 
half,  as  at  the  west  diastrophism  was  more  energetic,  and  at  the 
same  time  vuleanism  was  inaugurated  on  a  gi-eat  scale.  In  the 
plateau  region,  which  we  now  have  under  consideration,  the  dias- 
trophism was  chiefly  by  faults  and  monoclinal  flexures,  and  the 
whole  country  was  Itrokeu  into  gi'eat  irregular  blocks,  mainly 
by  lines  having  a  general  east-and-west  direction,  but  in  the 
soutlieast  a  north-and-south  direction.  At  the  north  the  blocks 
were  tilted  to  the  north,  but  there  were  many  minor  variations, 
and  in  the  south  they  were  tilted  to  the  east.  The  blocks  thus 
produced  are  the  gi'eat  plateaus,  which  were  modified  and  dis- 
sected by  rains  and  rivers.  At  the  time  when  these  movements 
began,  the  rocks  immediately  beneath  the  sea  were  lying  in  a 
horizontal  position  to  a  depth  of  many  thousands  of  feet.  When 
the  land  was  thus  upheaved  in  tilted  blocks,  tlio  strata  were 
slightly  inclined;  and  the  streams  heading  in  the  blocks  tilted 
northward  mainly  ran  northward,  with  branches  from  the  east 
and  west,  and  for  a  long  time  were  gathered  into  lakes  that 
drained  into  Colorado  Eiver,  while  in  the  south  they  drained 
chiefly  east  and  south  into  the  Eio  Grande  del  Norte.  As  general 
upheaval  went  on,  all  the  lakes  were  drained  by  the  cutting 
of  outlet  channels,  and  the  whole  region  became  arid.  All 
this  was  in  early  Neocene  time.  At  last,  in  late  Neocene  time, 
the  diastrophic  blocks  were  trenched ;  and  when  the  lakes  were 
drained,  their  bottoms  became  valleys,  and  the  valleys  were 
then  slightly  trenched  by  streams  running  into  the  Colorado 
and  Rio  Grande  del  Norte.  Thus  plateaus  of  great  diastrophic 
blocks  were  dissected  by  a  vast  network  of  streams.  The  up- 
turned edges  of  the  blocks  were  degraded  by  sapping, — a  pro- 
cess which  was  described  in  a  former  monogi-aph, — and  dias- 
trophic cliffs  were  carried  back  in  great  steps  or  teiTaces.  In 
this  manner  the  plateaus  were  still  further  dissected,  so  that  the 
whole  region  is  now  a  vast  assemblage  of  great  plateaus,  divided 
into  smaller  plateaus  by  the  channels  of  streams,  and  still  fur- 
ther divided  by  cliff's  produced  by  sapping.   In  general  the  entire 


92  PHYSIOGIUPHIC    KEGIONS    OF   THE    UNITED    STATES. 

region  is  a  group  of  tilted  blocks,  whose  higher  edges  termiuate 
in  gi-eat  cliffs  formed  by  sapping.  There  are  a  few  cliffs  which 
have  not  retreated  far,  and  still  mark  the  site  of  the  faults ;  while 
there  are  other  great  plateau  edges  which  are  nionoclinal  flex- 
ures, and  here  the  bent  rocks  yet  appear.  The  great  cliffs  are 
everywhei'e  adamantine  structures  of  magnificence:  they  are 
terraced  and  buttressed,  and  cut  with  deep  reentering  angles, 
and  often  set  with  towers,  pinnacles,  and  minarets;  they  ob- 
struct the  traveler  even  more  than  mountain  ranges;  in  fact, 
from  the  plain  below,  they  apjiear  as  mountains  built  of  naked 
rock.  Where  the  rocks  are  limestones  and  hard  sandstones, 
bold  precipices  are  formed ;  but  between  these  steep  ledges  the 
softer  shales  are  often  carved  into  a  filigree  of  fantastic  forms. 
A  facade  thus  constructed  of  rocks  of  varying  hardness  in  bands 
of  many  colors,  in  forms  that  resemble  Titanic  architecture, 
makes  the  scenerj^  a  constant  wonder  to  the  traveler.  Where 
the  edges  of  the  plateaus  are  nionoclinal  folds,  thc^  inclined  rocks 
are  carved  on  another  plan,  giving  variety  to  the  scenery. 

The  streams  usually  have  deep  channels.  Little  rills  born  of 
showers  and  <lying  with  the  sunshine  have  often  cut  deep  but 
narrow,  winding  gorges,  at  the  bottom  of  which  great  caves  are 
often  foTind.  The  creeks  have  cut  larger  canyons,  and  the 
rivers  have  cut  mighty  canyons,  —  gorges  sometimes  hundreds 
of  miles  in  length.  So  there  are  canyons  along  the  rivers, 
smaller  canyons  along  the  creeks,  still  smaller  canyons  along 
the  brooks,  and  pictui'esque  canyons  along  the  wet-weather 
rills;  and  tlie  plateaus  are  thus  divided  by  a  lab3'riuth  of  deep 
gorges.  While  the  diastrophism  of  the  blocks  has  produced 
gi'eat  plateaus,  and  while  stream  cutting  and  stream  sapping 
have  been  dissecting  them,  vuleanism  has  been  in  progress ;  and 
old  volcanoes  are  often,  found  on  the  summits  of  the  plateaus, 
and  cinder  cones  are  scattered  in  many  places,  and  great  sheets 
of  lava  have  been  poured  out  that  have  become  the  caps  of 
table  mountains,  and  other  sheets  have  been  piled  one  upon 
another  so  as  to  constitute  imbricated  mountains,  and  in  a  few 
places  laccolitic  mountains  are  found.  Thus  with  cliffs,  can- 
yons, gorges,  and  volcanic  mountains,  the  entire  region  is  one 
of  picturesque  grandeur. 

To  the  north  there  is  a  plateau  known  as  the  Uinta  Moun- 
tains, having  its  greatest  length  in  an  east-and-west  direction. 
It  has  a  mouoclinal  flexure  on  each  flank,  —  one  at  the  north 


COLOKADO   PLATEAUS.  93 

and  one  at  the  south.  Between  these  abrupt  flexures  the  rocks 
are  gently  carved.  Like  many  other  of  the  phiteaus,  the  south- 
ern edge  was  upheaved  much  more  than  the  northern  edge. 
This  plateau  was  dry  land  during  a  part  of  Cretaceous  time, 
and  there  were  islands  here  during  Eocene  time.  In  Neocene 
time  the  entire  plateau  became  dry  land,  and  from  that  time  on, 
the  rate  of  upheaval  was  comparatively  great,  and  through  this 
range  great  lakes  to  the  north  were  drained  into  lakes  farther 
south.  So  the  upheaval  went  on  as  the  plateau  was  lifted ;  but 
the  river  was  able  to  carve  its  way  through  the  plateau,  and  still 
remained  an  outlet  for  the  upper  lakes  during  all  Neocene  time. 
In  this  period  it  was  upheaved  more  than  twenty  thousand  feet, 
yet  the  river  cut  its  channel  and  preserved  its  course  during  all 
the  time.  The  river  came  from  the  north,  and  impinged  on  this 
block  about  halfway  in  its  course  from  east  to  west,  then  made 
its  way  into  the  heart  of  the  block,  next  tui-ned  eastward  for 
sixty  miles,  and  finally  turned  again  to  the  southwest,  until  it 
left  the  block  at  its  southern  margin.  So  the  canyon  was  cut 
through  a  bluff  that  was  slowly  lifted  by  forces  from  below. 

The  small  streams  have  all  trenched  deep  gorges,  between 
which  minor  plateaus  are  found ;  and  sometimes  the  trenching 
has  left  behind  gi-eat  peaks,  so  that  the  plateau  has  received  the 
name  "Uinta  Mountains."  It  is  largely  covered  with  forests,  but 
the  deep  gorges  often  have  cliffs  of  naked  rock. 

In  the  southeast  there  is  a  great  plateau,  on  the  western  side 
of  the  Rio  Grande  del  Norte,  opposite  the  Santa  Fe  Plateau.  The 
block  is  about  eighty  miles  square.  It  was  upheaved  from  the 
west  side  along  a  line  which  presents  a  general  north-and-south 
direction.  It  was  not  faulted,  but  upheaved  in  monoclinal  flex- 
ure, bringing  up  the  Neocene  rocks,  Cretaceous  rocks,  Juratrias 
rocks,  and  Carboniferous  rocks.  The  Cai'boniferous  rested  un- 
conformably  on  granite,  and  the  gi'anite  also  was  brought  up  to 
an  altitude  several  thousand  feet  above  the  little  valleys  on  the 
west.  Looking  at  the  edge  of  this  plateau  from  the  west,  it  ap- 
pears to  be  a  great  range  of  mountains.  The  block  itself  was 
tilted  eastward  and  to  a  sliglit  extent  southward.  As  it  came 
up,  the  Eocene,  Cretaceous,  and  Juratrias  rocks  were  all  washed 
away  from  the  western  margin  of  the  plateau,  leaving  a  summit 
of  granite ;  but  going  eastward,  rocks  of  all  of  these  ages  appejir 
in  order  from  the  older  to  the  younger.  As  the  block  was  tilted, 
there  was  very  little  vulcanism  on  its  western  flank,  but  on  the 


94  PHYSIOGiUrHIC    KEGIONS   OF   THE   UNITED   STATES. 

east  vast  bodies  of  lava  and  ashes  were  poured  out,  so  that  on 
this  eastern  margin  of  the  block  great  volcanoes  were  erected. 
The  emission  of  matter  from  below  was  accomplished  to  an  im- 
usual  extent  by  explosion,  so  that  vast  quantities  of  ashes  were 
ejected,  and  these  blew  over  the  plateau,  and  thus  beds  of  ashes 
scores  and  hundreds  of  feet  in  thickness  were  formed.  As  the 
volcanoes  and  ash  beds  were  constructed,  the  main  trend  of  the 
drainage  was  turned  southward  through  Jemez  River  and  its 
tributaries  by  a  ramifying  system  of  streams  from  the  north, 
east,  and  west.  Tliese  streams  have  often  carved  deep,  narrow 
canyons,  that  reveal  the  structure  of  the  vulcanic  rocks  above, 
and  the  sedimentary  rocks  below.  Space  forbids  the  further 
description  of  this  lieautiful  plateau,  ^"itli  its  granite  range  on 
the  west,  its  volcanic  peaks  on  the  east  and  north,  its  beautiful 
valleys  among  the  dead  volcanoes;  with  deep  gorges  through 
which  streams  run,  and  hot  springs  that  flow  from  the  vulcanic 
rocks,  and  curious  little  faults  that  appear  here  and  there,  and 
strange  forms  that  have  been  produced  by  corrasion,  and  lakes 
that  have  been  filled  and  di'ained,  and  the  forests  with  which 
the  plateau  is  crowned. 

To  the  south  the  San  Francisco  Plateau  is  found,  —  a  table- 
land of  gi-eat  extent.  It  was  upheaved  as  a  block  from  south 
of  west,  and  tilted  to  the  east.  All  the  Eocene  and  Cretaceous 
rocks  have  been  washed  away  from  its  summit,  and  are  found 
only  on  its  flanks;  but  portions  of  the  Juratrias  remain. 
Through  Eocene  time  it  was  deeply  trenched  by  many  streams. 
In  Neocene  time  vulcauism  prevailed,  and  a  great  system  of  vol- 
canoes was  built,  and  many  cinder  cones  are  found ;  often  old 
channels  were  fiUed  with  lava,  cinders,  and  ashes.  The  plateau 
is  quite  elevated,  and  the  rainfall  is  nearly  twenty  inches  an- 
nually; but  the  waters  thus  falling  on  the  surface  sink  away 
into  the  lavas,  cinders,  and  ashes,  and  are  gathered  below  at  a 
great  depth  in  the  old  stream  channels.  Sometimes  these  under- 
ground waters  excavate  great  caves  below,  and  then  the  upper 
rocks  fall  in,  so  that  many  sinks  are  formed.  In  one  of  the 
cinder  cones  a  crater  lake  is  found,  and  scattered  over  the  pla- 
teaus are  many  wonders.  It  is  covered  with  a  great  forest,  with 
intervening  prairies  that  are  gardens  of  wild  flowers  in  mid- 
summer. 

Only  three  of  the  plateaus  of  the  great  number  are  described, 
but  they  sei've  as  types  for  the  entire  region. 


THE   BASIN    KA.NGES.  95 


THE   BASEST   RANGES. 

South  of  the  Columbia  Plateaus,  and  west  and  south  of  the 
Colorado  Plateaus,  is  the  great  region  of  the  Basin  Ranges,  extend- 
ing far  down  into  Mexico.  It  is  a  region  of  isolated  diastrophic 
ranges,  usually  having  a  noi-th-and-south  direction,  and  often 
complicated  with  vulcanism.  The  blocks  out  of  which  the 
ranges  are  carved  are  uplifted  abruptly,  mainly  by  faults,  l^ut 
occasionally  by  steep  monocliual  flexures,  so  that  the  rocks  usu- 
ally dip  gently  away  to  the  other  side.  These  simple  diastrophic 
blocks  are  often  greatly  modified  by  vulcanism,  and  the  lava 
from  below  is  often  piled  up  in  peaks  and  small  plateaus,  while 
occasionally  volcanic  cones  are  found.  The  mountains  arc  never 
high,  and  are  often  destitute  of  large  trees,  and  sometimes  are 
mountain  deserts.  Between  these  isolated  ranges  there  ai"e 
broad  valleys  with  small  branches  extending  into  the  mountains. 
The  great  valleys  below  are  diastrophic  basins  which  receive  the 
sands  and  gravels  washed  down  from  the  mountains,  and  are 
filled  to  the  present  surface  from  great  depths  Itelow.  In  the 
mountains  themselves  narrow  valleys  have  been  trenched. 
Down  these  the  streams  flow  until  they  are  lost  in  the  sands, 
so  that  their  waters  are  not  carried  to  the  sea.  Sometimes 
there  are  salt  lakes  in  the  valleys.  Of  these.  Great  Salt  Lake 
and  Pyramid  Lake  are  the  more  important  examples.  In  early 
Pleistocene  time  there  were  many  njore  lakes  of  this  character ; 
and,  as  the  climate  was  more  humid,  some  of  them,  at  least, 
found  outlets  to  the  sea. 

The  region  is  naturally  divided  by  the  Colorado  River  of  the 
West.  The  district  to  the  north  is  characterized  mainly  by 
closed  basins,  though  near  the  Pacific  Ocean  there  are  many 
filled  valleys  which  drain  directly  into  the  sea,  and  near  the 
Colorado  thei'e  are  few.  Southeast  of  the  river  all  the  basins 
have  wet-weather  drainage  channels  into  the  great  river  itself 
and  the  Gulf  of  California,  or  into  the  Rio  Grande  del  Norte  and 
Gulf  of  Mexico.  The  entire  region  is  arid,  usually  having  less 
than  ten  inches  of  rainfall  annually  over  the  filled  basins.  It  is 
the  desert  region  of  tlie  United  States.  The  region  east  of  the 
Colorado  may  ultimately  be  distinguished  by  another  name: 
"  Sierra  Madre"  would  be  appropriate.  The  mountains  are  more 
diverse,  and  the  valleys  more  deeply  trenched. 


96  PHYSIOGRAI'HIC    UEGIONS    OF   THE    UNITED    STATES. 


PACIFIC   MOUNTAINS. 

This  is  a  great  gi'oiip  of  mouutaius  and  intervening  valleys. 
The  Cascade  region  is  a  diastrophic  plateau  on  which  vulcanic 
plateaus  have  been  piled,  aud  on  them  great  volcanoes  were  ele- 
vated which  are  now  extinct.  The  most  picturesque  peaks  in 
the  United  States  south  of  Alaska  are  here  found,  and  in  their 
gorges  glaciers  yet  remain.  From  the  crater  of  one  of  the  vol- 
canoes in  Oregon  there  have  been  vast  exjjlosions,  by  which  ashes 
and  cinders  were  scattered  widely  over  the  adjacent  country,  and 
afterward  the  rocks  about  the  crater  fell  into  the  depths  below. 
The  basin  thus  made  has  been  deeply  filled  by  snows  aud  rains, 
and  a  lake  has  been  formed  of  gi'eat  extent  and  depth,  known 
as  Crater  Lake.  To  the  west  of  these  mountains  a  river  flows 
northward  into  the  Colum])ia.  The  upper  part  of  the  valley  is 
comparatively  narrow ;  but  along  the  lower  two  thirds  there  is  a 
broad  stretch  known  as  the  Souud  Valley,  which  is  formed  by 
the  upheaval  of  the  Cascades  on  the  east,  and  of  the  mountains 
near  the  coast  on  the  west.  At  oue  time  an  arm  of  the  sea 
extended  up  this  valley  in  a  great  gulf,  and  since  that  time  the 
land  has  been  somewhat  uplifted.  It  is  thus  a  constructed  val- 
ley between  mountain  ranges,  and  has  been  partly  filled  with 
sediment.  To  the  west  the  Olympic  Mountains  stand  on  the 
north  of  the  Columbia.  The  structure  of  these  mountains  is  un- 
known. South  of  the  Columbia,  near  the  coast,  are  the  Oregon 
Mountains,  often  called  the  Oregon  Coast  Ranges. 

South  of  the  Sound  Valley  aud  the  Oregon  Ranges  there  is 
a  very  irregular  group  of  mountains,  drained  in  part  to  the  Co- 
lumbia, iu  part  to  the  Sacramento,  but  in  chief  part  directly  into 
the  ocean.  It  is  an  upheaved  archipelago  kuown  as  the  Klamath 
Mountains.  South  of  the  Cascade  Range  stand  the  Sierra 
Nevada.  It  is  a  great  block  upheaved  from  its  eastern  margin, 
and  tilted  westward.  The  displacement  is  by  a  complicated 
system  of  faults  and  folds,  along  which  there  has  been  much 
vulcanic  action;  and  the  coulees  of  lava  have  often  obstructed 
the  valleys,  and  formed  lakes  which  have  sometimes  been  filled 
by  sediments  until  they  were  di-ained  away.  One  of  these  streams, 
Ti-uckee  River,  has  its  source  far  back  in  the  block.  In  late 
Pleistocene  time  a  series  of  coulees  poured  across  it,  and  built  a 
dam  many  hundreds  of  feet  high,  behind  which  Tahoe  Lake  has 


rACU'IC    MOINTAIXS.  1)7 

been  gathered,  until  now  it  runs  over  the  dam,  in  which  it  lias 
cut  a  small  channel.  Elsewhere  in  the  Sierra  there  are  other 
lakes  having  internsting  histories.  As  the  l)lock  tilted  we.stwanl, 
the  drainage  is  chiefly  in  that  direction.  The  irrt'gular  streams 
have  carved  out  many  flaring,  steep  gorges,  between  which  moun- 
tain ridges  stand,  diminishing  in  altitude  to  the  vidh-y  of  (  ah- 
t'ornia.  Along  the  western  flank  there  has  been  much  vuh-an- 
ism;  and  the  coulees  have  formed  many  plateaus  which  have 
been  trenched  by  the  streams. 

To  the  west  of  the  valley  stand  the  North  and  South  Coast 
ranges,  which  are  mainly  anticlinal  folds,  sometimes  compressed 
and  faulted,  and  very  nuK-li  broken  into  fragments.  These  coast 
ranges  are  severed  where  the  San  Joaquin  joins  the  Saci-ameuto 
and  flows  through  the  Golden  Cltite  into  the  ocean.  The  bays 
about  San  Francisco  are  diastrophic  basins  modified  by  gradiv 
tion.  The  valley  of  ("alifornia  is  naturally  divided  into  two 
parts,  —  the  northern  valley,  drained  l)y  the  Sacramento;  the 
southern,  by  the  San  Joac^uin.  They  are  naturally  treeless, 
gently  rising  to  the  mountains  on  either  side.  Not  long  ago 
geologically  the  sea  occupied  these  valleys  as  a  great  gulf;  but 
they  liave  since  been  upheaved,  drained,  and  covei'ed  with  a  deep 
accumulation  of  clay  and  sand  washed  from  the  mountains. 

The  scenery  of  the  Pacific  mountain  region  is  greatly  diversi- 
fied, and  has  manj^  contrasting  f(>atur(>s.  Tlie  extinct  volcano(>s 
of  the  Cascade  Range  have  towering  peaks  that  are  covered  with 
snow  during  many  months,  whose  glittering  crowns,  revejded 
through  vistas  of  forest  land  or  seen  from  the  far-away  ocean, 
ever  inspire  delight.  With  green  forests  below,  gray  slopes 
above  the  forests,  and  peaks  of  silver,  their  symmetry  is  won- 
derful. This  aspect  of  the  mountains  entirely  changes  as  the 
mountaineer  ascends  from  valley  to  mountain  height;  then  the 
wooded  slopes  are  transformed  into  deep  gorgi's  covered  with 
evergreen  forests  of  giant  trees;  the  gi'ay  zone  above  is  trans- 
formed into  crags,  towei's,  and  minarets  of  many  but  f|uiet 
colors;  while  above  is  the  zone  of  silver,  with  its  snows  and 
glaciers.  So  the  mountains  are  in  uniform,  —  green,  gray,  ami 
silver, —  all  resplendent  in  noonday  sun.  When  tiie  clouils  come, 
the  peaks  are  masked;  but  as  they  vanish  or  roll  away,  a  chan- 
ging panorama  of  splendor  is  presented. 

The  Sound  Valley  is  mainly  covenvl  with  forests  of  trees,  tall 
and  statelv.     Amonii'  the  v(>nerable  ffiants  vounger  generations 


STATE  NORMALSOHOOL. 


\_' 


L'      ■ 

r.EtiF.SI':                      — 

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Uiina  are  calufil  Huff 

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tut       ■■         ■•       Blue 

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• 

loo  ruv.sKxiKAi'iiu    i;i:(ii()Ns  or  the  vniteu  states. 

live;  ami  pines,  lioinlocks,  and  cedars  lift  their  bourgeoning 
heads  to  vie  with  tlieir  elders.  On  the  gronnd  dead  and  pros- 
trate trunks  lie,  while  others  recline  against  the  living.  Among 
the  dead  and  living  trees  tliere  is  an  elaborate  interlacing  of 
vines,  creeping,  climbing,  twisting,  and  weaving  a  woof  of  \ine 
in  a  warp  of  branches.  Over  the  mountains  to  the  west  these 
forests  extend,  losing  but  little  of  their  luxuriance. 

Descending  from  ilount  Sliasta  into  the  valley  of  the  Sacra- 
mento, the  uortiiern  end  of  the  great  valley  of  California,  cinder 
cones  are  seen  in  great  numbers.  On  these  cones  tlie  rains  and 
snows  fall  and  sink  away,  to  reappear  far  away  in  great  springs. 
Then  the  tributai'ies  of  tlie  Sacramento  roll  down  in  deep  gorges. 
On  the  eastern  side,  and  on  to  the  south  for  five  hundred  miles, 
stretches  the  great  Sierra  Nevada,  with  toweriug,  irregular,  and 
dunisy  moimtains  on  its  eastern  margin,  cold,  gray,  and  deso- 
late. It  is  a  region  of  gorges  and  peaks,  but  at  their  feet  there 
are  many  beautiful  lakes  with  clear  emerald  waters.  Below  the 
peaks  is  a  region  of  forest.  The  traveler,  in  descending  west- 
ward to  the  valley,  passes  from  a  zone  where  forests  are  low 
and  gnarled  by  storms,  until  gradually  the  trees  become  more 
stately,  and  he  reaches  the  groves  of  sequoias,  —  the  great  trees 
of  the  world,  whose  mighty  forms  record  the  history  of  many 
centuries  of  winters  and  summers.  In  the  v;dley  below,  live- 
oaks  are  found  with  branches  akimlio,  and  knotted  fists  ready 
for  pugilistic  fray. 

Beyond  the  valley  are  the  Coast  Ranges,  where  the  balm  of 
the  tro])ics  loathes  the  winter  with  verdure,  and  boreal  zones 
lioon   the  snniiiK-r  with  zephyrs. 

The  Kockv  Mdcntaixs. — In  an  inipnrtaiit  sense  all  tlio  mountains  west  of  l)ii' 
(iveat  I'latenns  constitute  a  single  group,  though  the  regions  into  wliii-h  they  are  diviileil 
are  phiinlyileinarcated.  There  is  great  diversity,  ami  all  known  types  are  found;  and 
there  are  large  areas  of  jdateaus  and  still  larger  areas  of  valleys ;  yet  for  some  purposes 
it  is  convenient  to  use  a  general  term  for  them  all.  For  this  purpose  two  names  have 
been  used. —  "  Koeky  Mountains'' and  "Cordilleras."  The  term  "  Rocky  Mountains  " 
has  sometimes  been  applied  to  the  entire  group  of  groups,  both  by  writers  ami  in 
popuhir  s)ieech.  It  has  oftener  been  applied  in  a  vague  way  to  the  Stony  Mountains, 
the  Park  Mcumtains,  the  Columbia  Plateaus,  the  CoUu'ado  Plateaus,  and  a  part  of  the 
Hasin  Ranges,  especially  the  southern  district,  or  Sierra  Madrc.  The  term  "  Cordil- 
liras  "  has  been  used  by  a  few  writers  to  cover  the  same  region,  but  (lopular  usage  is 
confined  mainly  to  the  term  ••  Rocky  Mountains."'  This  name  has  liecn  useil  in  this 
broader  sense  to  cover  the  entire  region  by  the  officers  of  the  general  government,  and 
has  been  woven  into  the  federal  laws  with  this  meaning;  so  that  official  and  popular 
usage  coincide.  For  many  years  it  has  liccii  used  with  this  signi(ii-ani-e  by  the  presi'ut 
writiT. 


PRESENT  AND  EXTINCT  LAKES   OF   NEVADA. 


By  Israel  C.  Russell. 


TOPOGKAPHY  AND  CLIMATE  OF  NEVADA. 

The  traveler  who  crosses  the  State  of  Nevada  ou  the  Central 
Pacific  Railroad  will  observe  that  for  miich  of  the  way  the  route 
follows  the  Humboldt  River  and  crosses  the  "  grain  of  the  coun- 
try." The  mountain  ranges  trend  northeast  and  southwest,  and 
are  separated  by  level-floored  valleys.  The  valley  of  the  Hum- 
boldt, however,  is  a  striking  exception  to  this  rule.  The  river 
rises  on  the  eastern  border  of  the  State,  and  flows  westward 
for  half  its  length  before  conforming  with  the  direction  of  the 
mountain  ranges.  At  many  localities  the  traveler  can  see  far 
off  over  the  desert  valleys  to  the  right  and  left  of  his  course, 

-  and  cannot  fail  to  be  impressed  with  the  fact  that  the  dei)res- 
sioiis  between  the  sharp,  narrow  ranges  were  formerly  nuich 
deeper  than  now,  and  have  been  filled  in  or  gi-aded  up,  as  it 
were,  to  approximately  the  same  level. 

Could  the  traveler  scale  one  of  the  higher  peaks  that  he 

,  passes,  and  obtain  a  wide-reaching  view  over  the  i-iiggcd  land, 
the  fact  that  the  depressions  Ijetween  the  nKuuitain  ranges  have 
been  partly  filled  would  become  more  apparent.  In  general, 
the  central  parts  of  the  valleys  are  level-floored;  but  at  their 
borders  the  material  with  which  they  are  filled  slopes  upward, 
and  rests  against  the  rocky  sides  of  the  inclosing  mountains. 
The  sculpturing  of  the  mountains,  and  the  abrui)t  manner  in 
which  theii-  precipitous  sides  frequently  plunge  down  to  meet 
the  alluvium  in  the  valleys,  indicnte  the  de])t]i  to  which  their 
bases  have  become  buried.     Borings  through  the  soft  deposits 


(CopjTiglit,  1895,  by  Ameriean  Book  Company.) 
101 


10-  PRESENT  AND   EXTINCT  LAKES  OF  NEVADA. 

iu  the  valleys  show  that  their  rocky  bottoms  are  frequently  at 
least  two  thousand  feet  below  the  present  surface.  Careful 
estimates  based  on  the  character  of  the  mountain  slopes,  and  on 
borings  not  only  in  Nevada  Ijiit  over  a  much  larger  i-egion  of 
which  that  State  forms  a  typical  part,  indicate  that  iu  many 
instances  the  depressions  between  the  mountains  have  been 
filled  to  a  depth  of  at  least  foiu-  or  five  thousand  feet. 

Dirt  and  stones  have  beeu  washed  from  the  mountains  into 
the  adjacent  valleys,  and  graduallj'  reduced  the  inequalities  of 
the  surface,  but  still  the  topogi-aphy  remains  exceedingly  rugged. 
The  sharp,  angular  mountains  frequently  I'ise  from  four  to  six 
thousand  feet  above  the  neighboring  valleys.  The  coarser  mate- 
nal,  as  well  as  much  of  the  finer  debris  washed  from  the  uplands, 
has  beeu  deposited  about  the  mouths  of  the  gorges  through  which 
it  descended,  and  forms  broad  alluvial  cones.  The  accumula- 
tions about  the  entrances  of  adjacent  canyons  are  frequently 
confluent,  and  form  a  pediment  for  the  angular  peaks  that  seem 
to  rest  on  them.  The  margins  of  each  alluvial-filled  basin  slope 
down  in  gentle  curves  convex  to  the  sky,  and  mei'ge  into  the 
broad  level  area  in  the  central  part  of  the  depression.  When 
the  openings  between  adjacent  valleys  are  wide,  the  matenals 
iu  their  bottoms  are  imited  in  such  a  manner  as  to  form  a  single 
plain,  thi'ough  which  the  higher  summits  of  the  partially  buried 
ranges  project,  and  form  island-like  elevations  known  as  lost 
moiuitahti. 

The  topogi'aphy  is  strikingly  at  variance  with  that  of  regions 
having  an  al  )undant  and  well-developed  drainage.  Many  of  the 
valley  bottoms  are  micut  by  stream  channels,  and  are  so  inclosed 
by  mountains  that  they  would  hold  bi'oad  lakes  before  being 
filled  to  overflowing.  Scores,  if  not  Inmdreds,  of  such  basins 
exist,  but  lakes  are  rare. 

The  traveler  who  visits  Nevada  will  be  impressed  also  with 
the  arid  and  frequently  decidedly  desert  character  of  the  coun- 
try. Forests  are  absent,  excejit  in  a  few  limited  areas  on  the 
higher  mountains.  One  may  ride  for  hundreds  of  miles  through 
the  valleys  without  finding  a  tree  to  shelter  him  from  the  in- 
tense heat  of  the  summer  sun.  The  prevailing  vegetation  is  the 
sagebrush  {Artemisia).  This,  with  other  desert  shrubs,  imparts 
a  gray  tint  to  the  russet  brown  of  the  naked  land.  For  months 
together  not  a  drop  of  rain  falls,  and  for  weeks  in  succession 
the  sky  is  without  a  cloud. 


TOPOGKAPHY   AND   CLIMATE   OF   NEVADA.  103 

Uu  the  raiii  charts  recently  issued  by  the  U.  S.  Weather 
Bureau,  the  rainfall  of  Nevada  during  the  three  mouths  of 
spring,  with  the  exception  of  a  small  area  at  the  north,  is 
below  ten  iuches,  and  over  a  considerable  portion  of  the  west- 
central  part  is  less  than  one  inch.  In  summer  it  is  less  than 
one  inch,  and  in  fall  and  winter  less  than  three  iuches,  for  the 
entire  Htate.  The  precipitation  for  the  year  is  represented  as 
being  less  than  ten  inches,  and  over  a  large  area  in  the  west- 
central  part  is  below  five  inches.  The  obsei-vatious  on  which 
these  generalizations  are  based  were  made  from  the  early  settle- 
ment of  the  country  to  the  close  of  1891,  principally  along  the 
railroads,  and  do  not  show  the  depth  of  precipitation  on  the 
mountains.  They  fail  to  some  degree,  also,  in  expressing  the 
extreme  aridity  of  some  of  the  valleys  in  the  western  and  cen- 
tral jKU'ts  of  the  8tate,  for  the  reason  that  at  times,  as  I  have 
been  informed  by  settlers,  there  is  no  rain  at  all  in  those  regions 
during  eighteen  or  more  consecutive  months. 

In  contrast  with  the  exceedingly  arid  character  of  Nevada, 
I  may  recall,  for  the  sake  of  illustrating  by  contrast,  the  fact 
that  in  the  Mississippi  Valley  the  mean  annual  precipitation  is 
from  30  to  40  inches,  increasing  southward  to  50  or  (iO  inches. 
In  portions  of  Florida  and  on  the  coast  of  North  Carolina  it 
exceeds  60  inches,  and  on  the  coast  of  the  State  of  Washingtou 
is  more  than  100  inches. 

One  other  series  of  facts  in  the  jihysiography  of  Nevada 
should  be  borne  in  mind  by  the  student  who  wishes  to  know  the 
life  history  of  her  lakes. 

The  small  rainfall  and  clear  skies  are  accompanied  by  a  high 
mean  annual  temperature.  The  humidity  of  the  titmosjjhere  is 
low,  aud  evaporation  excessive.  The  annual  loss  by  evaporation 
from  a  surface  of  standing  water  exposed  to  the  sun  and  winds 
ranges  from  70  to  more  than  100  inches.  On  a  given  area  in  the 
valleys  the  amount  of  water  that  could  be  evaporated  annually 
is  from  20  to  80,  and  in  exceptional  years  100,  times  the  meau 
annual  precipitation. 

The  marked  diversity  in  the  relief  of  the  land,  and  the  char- 
acter of  the  climate,  determine  the  principal  episodes  in  the  his- 
tories of  the  lakes  to  which  attcMition  is  here  invited. 

Many  of  the  valleys  are  1)road  aud  deep.  Under  more  favor- 
able climatic  conditions,  they  would  be  transformed  into  exten- 
sive lakes,  but  at  present  arc!  without  standing  water  throughout 


104  PRESENT  AXD  EXTINCT  LAKES  OF  NEVADA. 

the  year.  The  deep  porous  soil  acts  like  a  spouge,  and  is  capable 
of  retaiuiug  much  more  water  than  the  clouds  now  furnish. 

There  is  a  second  som-ce,  however,  from  which  the  desert 
valleys  derive  water,  that  must  not  be  ignored. 

The  long  parallel  mountain  ranges  are,  as  a  lode,  steep  on 
one  side,  and  slope  much  more  gently  iu  the  opposite  direction. 
Each  of  these  sharji,  narrow  ranges  is  the  upturned  edge  of  a 
block  of  the  earth  crust,  separated  from  the  adjacent  block  by 
profound  fractui-es.  The  fractui'e  which  permitted  this  unequal 
tilting  commonly  follows  the  base  of  the  steeper  side  of  a  range, 
while  the  depressed  border  of  the  fractm-e  underlies  a  partly 
filled  valley.    This  "  basin  range  stnicture  "  is  shown  in  the  ac- 

iMke  Range.  Winn<-mnrrn       -Vafhe  Roiioc 

Piiramul        jk^,^  "  »'nemucca 

'L<ih(.  j^ Lnh, 


jri.-(. 

Ideal  Section  through  Pyramid  and  Winnemucca  Lakes,  Nevada. 

companj'ing  generalized  section.  The  breaks  refeired  to  fre- 
quently admit  of  the  escape  of  water  from  soiu'ces  deep  below  the 
sm'face,  and  copious  sj^riugs  result.  In  many  instances  the  water 
flowing  from  these  fissures  is  highly  heated,  showing  that  it  rises 
from  such  a  depth  that  its  temperature  is  raised  on  account  of  the 
general  interior  heat  of  the  earth,  or  else  that  the  walls  of  the  fis- 
sure have  undergone  recent  movement,  and  by  their  friction  ele- 
vated the  temperature.  These  fissure  springs  are  fed  by  the  rain 
falling  on  distant  regions,  no  one  kiidws  where,  and  furnish  an  im- 
portant adjunct  to  the  meager  rainfall  in  the  region  where  they 
rise.  Much  of  Nevada  would  be  impassable  in  summer  were  it 
not  for  the  waters  that  reach  tlie  desert  valley  through  fractures 
iu  their  bottoms.  The  spring  waters  bring  with  them  large 
quantities  of  mineral  matter  in  solution,  which  is  added  to  the 
lakes  to  which  they  may  become  tributaiy,  or,  when  evaporated 
from  the  adjacent  surfaces,  appeal's  as  a  white,  saline  incrustation. 

THE  PRESENT   L.VKES. 

The  nature  of  the  topogi-aphy  of  Nevada,  and  the  character 
of  the  climate,  lead  to  the  formation  of  two  classes  of  water 
bodies.  These  may  for  convenience  be  designated  as  ephemeral 
lakes  and  perennial  lakes.    The  former  are  especially  character- 


EPHEMEKAL  LAKES.  lUd 

istic  of  the  vast  arid  region  of  which  Nevada  is  a  typical 
part,  and  merit  theii"  name  because  of  their  brief  existence;  the 
latter  hold  their  autonomy  for  many  consecutive  years,  and  even 
for  centmies,  and  are  fresh  or  saline  according  as  they  ovei"flow 
or  are  completely  landlocked. 

Ephemekax,  Lakes. — Could  one  be  so  situated  as  to  obtain  a 
bird's-eye  view  of  Nevada,  and  watch  the  coming  and  going  of 
the  seasons,  the  manner  in  which  many  lakes  are  liorn  in  the 
desert  valleys,  live  their  l^rief  lives,  and  pass  away,  would  appear 
like  the  changing  views  in  a  panorama. 

When  the  clouds  gather  in  dark,  gloomy  masses  aboiit  the 
mountain  tops,  and  gradually  expand  until  they  bridge  over  the 
intervening  basins,  the  rain  falling  from  them  descends  most 
abundantly  on  the  uplands,  and  in  less  quantity  on  the  parched 
valleys.  Sti'eams  fed  .by  the  falling  raindrops  course  down  the 
mountains,  washing  away  the  loose  material  that  frecjiiently 
clogs  their  channels,  and  reach  the  valleys  heavily  loaded  with 
silt,  and  not  infrequently  roll  along  bowlders  many  tons  in 
weight.  These  roaring  torrents  sometimes  disappear  beneath 
the  surface  on  reaching  the  border  of  a  valley,  and  add  their 
loads  to  the  deposits  left  by  previous  floods.  The  water  that 
thus  disappears  emerges  again  when  the  subsoil  becomes  sat- 
urated, and  gathers  in  the  lowest  depressions.  The  streams 
that  are-  not  wholly  al)Sorbed  by  the  porous  alluvium  flow  on 
with  diminished  volume  in  bifurcating  chaiuiels,  and,  tojivtlicr 
with  the  rain  that  falls  in  the  valley,  finally  spread  out  and  form 
shallow  lakes.  Should  the  storm  continue,  the  sheets  of  water 
in  the  valleys  will  expand,  and  possibly  become  many  square 
miles  in  area.  Such  lakes  are  always  shallow,  and  always 
yellow  with  mud  in  suspension.  When  the  sun  breaks  through 
the  storm  clouds,  evaporation  becomes  active,  and  the  lakes  gi'ad- 
ually  contract  their  boundaries,  and  perhaps  in  a  few  lioui-s  or 
in  a  few  days  are  entirely  dissipated.  When  the  water  has  dis- 
appeared, absolutely  barren  mud  plains  remain,  which  harden 
under  the  sun's  heat,  and  become  cracked  in  all  directions  as  their 
surface  contracts  in  drying.  The  lake  beds  then  have  a  striking 
resemblance  to  tessellated  pavements  of  cream-colorcnl  marble, 
and  soon  become  so  hard  that  they  ring  beneath  the  hoof  beats 
of  a  galloping  horse,  but  retain  scarcely  a  trace  of  his  foot- 
prints. 

Such  bare,  level  mud  plains  are  characteristic  features  of  the 


lOG  PRESENT   AND   EXTINCT  LAKES   OF   NEVADA. 

greater  part  of  the  valleys  of  Nevada,  and  are  known  iu  Mexico 
aud  adjacent  portions  of  the  United  States  as^^/rty/o.^.  The  lakes 
to  which  they  owe  their  origin  are  termed  plai/a  lakes. 

These  ephemeral  water  bodies  frequently  come  aud  go  almost 
as  erratically  as  the  shadows  of  the  clouds  cast  on  their  own 
tawny  surfaces.  In  other  iustauces  lakes  of  the  same  type 
appear  during  the  winter  months,  and  remain  until  the  heat  of 
summer  reaches  a  maximum ;  they  then  give  place  to  smooth 
plains  of  mud  of  the  same  character  as  those  left  by^the  more 
transient  water  sheets.  Still  other  playa  lakes  are  for  a  time 
pereunial,  and  only  evaporate  to  dryness  diu-ing  seasons  of 
imusual  aridity.  The  playa  lakes  with  long  periods  of  oscilla- 
tion approach  the  condition  of  the  lakes  which  have  ne^^er  been 
knowu  to  become  dry.  Ephemeral  aud  perennial  water  bodies 
are  thus  united  in  one  series.  Thei'e  is  no  I'igid  Ijoundary  be- 
tween them;  but  it  is  convenient  to  select  well-marked  tj-pes 
to  stand  as  representations  of  the  two  extremes,  just  as  the 
naturalist  does  when  he  di"vidcs  animals  into  genera. 

Lakes  of  the  Black  Bock  and  Smoke  Ceeek  Desekts. — 
The  largest  ephemeral  lake  of  Nevada  is  foimed  during  winter 
months  on  what  is  knowu  as  Black  Rock  Desert  in  the  north- 
western part  of  the  State  (see  Plate  I.).  This  desert  valley  is 
irregular  in  shape,  and  has  lateral  valleys  opening  from  it.  Its 
length  from  northeast  to  southwest  is  over  one  hundred  miles, 
aud  its  average  breadth  twelve  or  fifteen  miles.  In  summer  it  is 
almost  entirely  without  tributary  streams,  except  such  as  are  fed 
by  hot  springs.  In  winter  many  brooks  descend  the  mountains 
to  the  east  and  west;  and  the  channel  of  Quinn  River,  which 
enters  the  basin  from  the  northeast,  is  transformed  into  a  veri- 
table river.  The  course  of  this  stream  in  summer  is  marked 
only  by  a  diy  channel,  with  an  occasional  water  hole;  but  in 
winter  it  is  flooded  so  as  frequently  to  be  impassable  to  a  man 
on  horseback,  aud  has  a  length  of  upward  of  a  hundred  miles. 
Its  watei-s  then  spread  out  on  Black  Rock  Desert,  and  at  times 
form  a  long  uaiTow  lake  from  450  to  500  square  miles  in  area. 
Although  seldom  over  a  few  inches  deep,  it  is  impassable  on 
account  of  the  softness  of  the  mud  forming  its  bottom.  Many 
times  the  "lake"  is  a  vast  sheet  of  liquid  mud,  and  for  this 
reason  is  knowu  as  "Mud  Lake"  by  the  settlers  of  the  region. 
This  name  is  not  distinctive,  however,  as  many  other  playas 
have  the  same  name  attached  to  them. 


SEMIPEUENNIAX  LAKES   OF   CAKSON   DESERT.  107 

Black  Eock  Desert  is  uot  closed  at  its  southern  eutl,  but 
opens  out  iuto  another  deep  basin,  known  as  Smoke  Creek 
Desert.  At  the  place  of  union,  rocky  headlands  project  from 
the  mountains  on  the  east  and  west,  and  approach  within  about 
five  miles  of  one  another.  Where  this  constriction  occurs,  tliere 
is  a  slight  rise  in  the  valley  bottom,  but  sufficient  to  divide  the 
water  that  enters  the  basin  and  leads  to  the  formation  of  two 
lakes.  The  lake  formed  during  the  winter  on  Smoke  ('reck 
Desert  is  not  as  large  as  its  companion  to  the  north,  Init  is 
sometimes  25  to  30  miles  long  and  5  miles  wide.  In  all  of  its 
essential  featui-es  it  is  a  counterpart  of  the  one  just  described. 

The  winter  lakes  on  Black  Eock  and  Smoke  Creek  deserts, 
as  in  many  other  similar  instances,  do  not  occupy  the  entire 
valley  bottom,  but  are  suri-ounded  by  a  broad  fringe  of  what  to 
the  eye  appeai-s  level  land.  This  l)roadening  tract  is  covered 
with  sagebrush  and  other  desert  shrubs.  In  early  spring  many 
flowers  beautify  the  ground,  and  fill  the  air  with  a  faint  pei-fume. 
The  playas  left  by  the  desiccation  of  the  lakes,  however,  are 
always  barren.  Not  a  plant  takes  root  in  their  baked  and  har- 
dened surfaces.  Where  these  mud  plains  meet  the  surrounding 
areas  clothed  with  desert  shrubs,  there  is  often  a  belt  of  ground 
that  is  soft  and  marshy  in  winter,  and  frequently  retains 
something  of  this  character  after  the  lakes  have  disap{)eared. 
In  summer  it  Ijecomes  white  with  salts  brought  from  below  )»y 
ascending  water,  and  left  on  the  surface  when  evaporation  takes 
place.  These  efflorescent  deposits  become  unusually  alauidaut 
about  some  of  the  hot  springs,  and  are  then  apt  to  contain  borax 
in  addition  to  the  sulphate  and  carl)onate  of  soda,  common  salt, 
etc.,  which  make  uji  the  bulk  of  such  incrustations. 

Lakes  of  Carson  Desert. — The  Carson  Desert  in  west-cen- 
tral Nevada,  shown  on  the  niaj)  forming  Plat(>  T.,  is  a  l)asin  sur- 
rounded by  irregular  mountains.  Its  length  from  northeast  to 
southwest  is  about  75  and  its  width  25  miles.  It  receives  the 
waters  of  Carson  and  Humboldt  rivers,  but  has  no  channel  of 
escape.  Both  of  these  streams  are  Avorthy  to  rank  among  rivei's, 
if  their  length  and  volume  in  the  winter  season  are  alone  con- 
sidered. 

Carson  Eiver  rises  on  the  eastern  slope  of  the  Si(>rra  Nevada, 
and  has  a  length  of  125  miles  and  a  tlrainage  area  of  about  1,000 
square  miles.  Humboldt  Eiver  is  fully  300  miles  long,  and  drains 
a  region  of  small  rainfall,  in  wliicli  the  divides  are  frequently 


108  PRESENT  .VND   EXTINCT  LAICES   OF  NEVADA. 

indistiuguisliable.  The  area  of  its  hydrographie  basiu  may  be 
variously  estimated,  but  is  iu  the  ueighborhood  of  7,000  or  8,000 
square  mUes.  This  is  the  largest  stream  that  has  its  source 
iu  the  central  area  of  the  arid  region  of  which  Nevada  forms 
a  typical  part,  and  is  abnormal  iu  several  particulars.  Each 
of  these  streams  is  exceedingly  variable  in  volume.  In  winter 
they  carry  several  hundred,  in  the  case  of  the  Carson  River 
fifteen  hundred,  times  as  much  water  as  during  the  average 
summer  stage. 

The  waters  of  the  Carsou  and  Humljoldt  spread  out  on  the 
Carson  Desert,  and  ai-e  there  evaporated.  When  flooded,  they 
form  two  sheets  of  water,  known  as  North  Carson  and  South 
Carson  lakes.  These  lakes  are  frequently  designated  as  "The 
Sink  of  the  Humboldt"  or  "  Humboldt  Sink,"  and  "  The  Sink  of 
the  Carson ; "  the  popular  beUef  being  that  the  waters  escape  by 
subterranean  outlets,  or  sink  below  the  sm-face.  This  is  not  the 
case,  however,  as  it  can  be  proven  that  the  infloAv  is  counterbal- 
anced solely  Ijy  evaporation.  North  Carsou  and  South  Carson 
lakes  are  of  the  playa  type,  but  are  more  persistent  than  the 
lakes  of  Black  Rock  and  Smoke  Creek  deserts.  They  some- 
times hold  their  integrity  for  a  succession  of  years,  but  evap- 
orate to  drjTiess  during  seasons  of  more  than  usual  aridity. 
North  Carson  Lake  is  rudely  elliptical  in  outline,  and  is  from  20 
to  25  miles  across  from  east  to  west,  and  about  14  miles  broad 
from  north  to  south.  That  its  depth  is  never  over  a  few  feet, 
has  been  shown  by  examining  its  bed  when  dry. 

South  Carson  Lake,  when  at  its  maxinuim  as  known  in 
recent  years,  is  from  4  to  5  miles  in  diameter,  and  aliout  4  feet 
deep.  Its  depth  is  unusual  for  a  playa  lake;  and  for  this 
reason,  and  because  its  feeding  stream  rises  iu  high  mountains, 
it  is  more  constant  than  many  other  examples  of  its  class. 

Variations  in  the  extent  of  the  lakes  of  the  Carsou  Desert 
have  been  more  marked  in  recent  years  than  formerly,  for  the 
reason  that  the  streams  supi^lying  them  are  being  used  for  irri- 
gation. They  are  now  more  apt  to  become  dry,  and  pass  to  the 
condition  of  playas  during  the  summer,  than  when  first  known 
to  the  settlers  of  the  region.  They  still  serve,  however,  to  show 
the  connection  that  exists  lietween  the  ephemeral  lakes  born  of 
a  single  shower,  and  evaporated  to  drjniess  after  a  day  or  two 
of  sunshine,  and  perennial  water  bodies  that  eudm-e  for  a  term 
of  years. 


SEMIPEKENNIAL   LAKES   OF   EASTEKX    XEVADA.  109 

LaivES  of  OTHER  INCLOSED  Basins.  —  Diamond  valley,  to  the 
north  of  Eureka,  furnishes  another  example  of  the  manner  in 
which  a  delicate  balance  between  precipitation  and  evapora- 
tion leads  to  striking  changes  in  the  aspect  of  an  inclosed  basin. 
In  summer  this  valley  is  exceedingly  desolate,  and  a  part  of 
its  area  is  white  with  salt.  In  winter  the  streams  from  the  sur- 
rounding mountains  are  revived,  evaporation  decreases,  and 
a  lake  is  formed  in  the  lower  part  of  the  depression.  The 
previously  precipitated  salts  which  give  the  desert  something 
of  a  wintry  aspect  during  months  of  excessive  dryness,  are 
dissolved,  and  a  lake  similar  in  appearance  to  the  normal  lakes 
of  humid  regions  appears  in  its  place.  Year  after  year  this 
fluctuation  goes  on,  and  the  appearance  of  the  valley  changes 
in  sympathy  with  the  iinseen  forces  that  control  tem])erature 
and  humidity.- 

In  the  central  part  of  the  area  of  interior  drainage  between 
the  Sierra  Nevada  and  Wasatch  Mountains,  there  rises  a  con- 
spicuous range  known  as  the  East  Humboldt  Mountains.  These 
are  snow-capped  in  winter,  and  repeat  on  a  smaller  scale  many 
of  the  conditions  resiilting  from  the  gi'eat  elevation  of  tli<'  nu)un- 
tains  bordering  Nevada  on  the  west. 

To  the  east  of  the  East  Humboldt  Mountains  there  are  three 
lakes,  known  in  their  order  from  south  to  north  as  Ruby,  Frank- 
lin, and  Eagle  lakes.  These  hold  the  same  relation  to  th(»  lofty 
peaks  adjacent  to  them  on  the  west  as  Pyramid  and  other  lakes 
to  be  described  occupy  with  respect  to  the  Sierra  Nevada.  The 
lives  of  the  lakes  supplied  by  the  drainage  of  the  East  Hum- 
boldt Range  are  less  secure,  however,  than  in  the  case  of  the 
larger  lakes  fed  by  streams  from  the  gi*eater  range  to  the  west. 
In  winter  they  are  flooded,  the  water  supply  being  in  part  fur- 
nished by  fissure  springs;  and  in  summer  they  decrease  in  area, 
and  occasionally  their  basins  l)ecomc  dry. 

Ruby  Lake,  when  in  its  normal  winter  contlition,  is  about 
16  miles  long,  and  has  a  nearly  uiiirorm  width  of  perhaps  '2  miles. 
It  is  separated  from  Franklin  Lake,  to  the  north,  by  a  narrow 
gravel  bar  formed  by  waves  and  currents  in  an  extinct  water 
body  much  larger  than  both  of  the  present  lakes  combined. 
Franklin  Lake  is  15  miles  long,  with  an  average  width  from  east 
to  west  of  4  miles.  Eagle  Lake,  '-2  miles  imrtliward  from  the  one 
jiist  mentioned,  is  more  irregular  than  its  companions,  and  is 
about  7  miles  in  diameter. 


110  TEESEXT   AND   EXTINCT   LAKES   OF   NEVADA. 

The  watei's  of  these  lakes  are  shghtly  alkaliue,  but  in  wiuter 
and  spriug  are  not  unpleasant  to  the  taste.  They  are  playa 
lakes  with  a  longer  period  than  most  of  tlieir  companions  of  the 
same  t^1^e,  and  might  with  propriety  be  termed  scmiperciDiidl. 
To  this  iirovisional  subclass  might  also  be  refeiTed  the  lakes  of 
the  Carson  Desert,  since,  previous  to  the  time  their  tributary 
streams  liegan  to  be  diverted  for  irrigation,  they  were  e\ap- 
orated  to  dryness  only  in  occasional  years  of  gi'eat  aridity. 

Hundreds  of  other  inclosed  basins,  jiarticidarly  in  southern 
Nevada,  are  partially  flooded  in  winter  in  a  similar  manner  to 
those  already  enumerated,  and  become  desert  plains  of  hardened 
mud  in  sunmier.  Various  jiortions  of  the  region  surrounding 
Nevada,  and  especially  those  embraced  ■within  the  boundaries  of 
Utah,  Arizona,  and  California,  experience  changes  similar  to 
those  just  described,  and  illustrate  some  of  the  most  striking 
peculiarities  of  a  region  where  the  topogi-aphic  and  climatic 
conditions  favor  the  existence  of  temporary  lakes. 

Perexxlu.  Lakes. — Lakes  which  exist  for  a  term  of  years, 
and  hence  termed  ju'rennial,  may  be  convenientlj'  divided  into 
two  classes:  namely,  those  that  overflow,  or  normal  lakes:  and 
those  that  do  not  rise  sufficiently  to  find  an  outlet,  or  inclosed 
lakes.  By  normal  lakes  is  meant  the  class  of  lakes  characteristic 
of  humid  regions,  and  hence  the  most  abundant  and  most  famil- 
iar the  world  over.  They  are  commonly  expansions  of  rivers, 
and  overflow. 

These  two  subclasses,  as  in  the  case  of  ephemeral  and  peren- 
nial lakes,  are  not  limited  1  >y  definite  Ijoundaries.  Inclosed  lakes 
are  sensitive  to  climatic  changes,  and  may  increase  in  vohime 
until  their  surfaces  are  raised  to  the  level  of  the  lowest  point  in 
the  rims  of  their  basins,  and  be  transferred  temjxirarily  or  i:)er- 
manently,  if  the  climatic  conditions  remain  favorable,  to  the  list 
of  those  which  usually  give  origin  to  streams.  Numerous  exam- 
ples in  Nevada  and  adjacent  regions  might  be  cited  of  lakes 
which  have  been  known  to  undergo  changes  that  have  transferred 
them  many  times  from  one  sul)class  to  another. 

Some  of  the  ephemeral  lakes  of  Nevada  which  are  not  suflS- 
ciently  permanent  to  have  a  name,  or  to  be  recognized  as  lakes 
l)y  the  settlers  of  the  region  where  they  occur,  o\erflow  during 
their  brief  existence,  and,  if  this  one  feature  is  alone  used  in 
classification,  would  belong  to  the  class  of  water  bodies  charac-. 
teristic  of  humid  regions.     It  will  be  seen,  therefore,  that  the 


NORMAL   PEKENNIAl,   LAKES.  Ill 

classification  i)iopu.sed  aljuve  is  simply  for  (•onvenicucc,  and  does 
not  imply  stable  conditions. 

NoKMAL  Lakes. — The  list  of  normal  lakes  in  Nevada  is  short. 
There  ai-e  two  only — Lake  Tahoe  and  Lake  Humboldt — that  can 
consistently  Ije  placed  in  the  same  category  as  the  tens  of  thou- 
sands of  lakes  found  in  humid  regions. 

Lake  T((hoe.  —  This  "  ({em  of  the  Sierras,"  as  it  has  been  a])tly 
called,  is  situated  partly  in  Nevada  and  partly  in  California. 
The  depression  it  occupies,  like  the  majority  of  the  basins  de- 
scribed in  this  paper,  was  foi-med  by  unequal  movement  of  lai'ge 
masses  of  the  earth's  crust  ((UasfropliisDi).  The  outline  of  tlie 
valley  in  the  mountains  which  the  lake  has  ajipropriated  has  been 
modified  to  some  extent  by  streams  and  glaciers,  but  not  suffi- 
ciently t(^  destroy  the  characteristic  features  resulting  fi-om  the 
great  disturljances  that  gave  it  birth. 

Lake  Tahoe  is  surrounded  by  some  of  the  finest  scenery  of 
the  Sierra  Nevada,  and  is  especially  pleasing  on  account  of  the 
breadth  of  view  obtained  from  many  jtoints  on  its  sliores.  The 
mountains  surrounding  it  are  clothed  with  coniferous  forests  to 
within  a  few  hundred  feet  of  .their  angular  summits.  Their  more 
rugged  lines  are  thus  subdued,  and  given  a  picturesqueness  that 
is  entirely  lacking  on  the  shores  of  the  desei't  lakes. 

This  lake  is  21  miles  in  diameter  from  north  to  south,  and  1 2 
from  east  to  west.  It  is  195  square  miles  in  area,  and  receives 
the  drainage  of  922  square  miles  of  territory.  Its  elevation 
above  the  sea  is  t),202  feet.  Soundings  made  l)y  Professor  John 
Le  Conte  gave  a  depth  in  the  central  part  of  1,(545  feet.  This 
measure  maybe  exceeded  when  a  morc^  systematic  survey  of  the 
contour  of  the  bottom  is  made.  Next  to  Crater  Lake,  ( )regon,  it 
is  the  deepest  lake  yet  measured  in  North  America.  Its  waters, 
of  gi'eat  pm'ity  and  of  wonderful  transparency,  are  inhabited  1)y 
splendid  trout  and  other  fishes  in  abundance.  The  overflow 
escapes  through  a  rocky  gorge,  and  foi'ins  Truckee  River, — a 
clear,  swift  stream,  which,  after  a  tortuous  course  of  about  100 
miles,  empties  itself  into  Pyramid  aud  Winn(Mnucea  lakes. 

Lake  Tahoe,  situated  among  mountains  that  rise  tVom  seven 
to  ten  thousand  feet  above  the  sea,  the  swift  bright  rivei-  flowing 
from  it,  and  the  alkaline  and  saline  lakes  formed  by  the  retention 
of  its  surplus  waters  in  desert  valleys,  furnish  a  geogi-aphical 
unit  in  which  many  of  the  marked  contrasts  between  humid 
and  arid  lands  are  Avell  illustrated.     A  careful  study  of  this 


112         PUESEXT  AXD  EXTINCT  LAKES  OF  NEVADA. 

single,  eireumscnbed  drainage  area  would  furnish  one  of  the 
most  complete  and  instructive  lessons  in  physical  geography 
that  our  country  affords. 

Jlouiitain  Tania. — To  make  an  account  of  the  existing  lakes 
of  Nevada  complete,  it  is  necessary  to  mention  a  few  small  tarns 
situated  in  deep  recesses  on  some  of  the  higher  mountains.  In 
the  portion  of  the  Sierra  Nevada  included  within  the  boundaries 
of  the  State,  on  the  East  Humboldt  Eange,  and  about  Jeff  Davis 
Peak,  there  are  small  basins  at  elevations  of  from  eight  to  ten 
thousand  fi»et  above  the  sea,  which  are  filled  usually  to  over- 
flowing with  clear,  sweet  water.  These  depressions  are  either 
in  solid  rock,  or  are  formed  in  part  by  terminal  moraines  left 
by  ancient  glaciers.  They  are  of  a  type  common  in  mountains 
that  have  been  ice-covered,  but  are  exceptional,  and  are  not  a 
characteristic  feature  of  the  arid  region  in  which  we  ai"e  now 
especially  interested. 

Hitmholdt  Lah'. — Huml>oldt  River,  after  flowing  for  some 
three  hundred  miles  through  treeless  valleys,  and  just  before 
reaching  the  Carson  Desert,  meets  an  obstruction  that  holds  its 
waters  in  check,  and  causes  an  expansion  known  as  Humboldt 
Lake.  The  dam  which  blocks  the  way  is  an  immense  gravel  bar 
which  extends  completely  across  the  valley,  and  was  formed  in  an 
extinct  lake  (Lake  Lahontan,  to  be  described  later).  This  bar,  as 
may  lie  seen  from  the  map  forming  Plate  IV.,  has  many  of  the 
features  of  a  railroad  embankment.  It  is  formed  mostly  of  gravel 
and  sand  swept  from  the  margins  of  the  old  hxke  and  deposited  in 
deeper  water  when  the  loaded  currents  were  deflected  from  the 
shore.  Its  length  from  the  cliffs  on  either  side  of  the  valley  is 
about  4  miles.  Its  top  is  from  50  to  125  feet  above  the  adjacent 
phun.  The  river  was  held  in  check  by  this  obstruction  when  the 
old  lake  was  lowered  below  its  crest  and  formed  a  secondary  lake. 
At  some  time  in  its  history  the  lake  overflowed,  and  cut  a  narrow 
channel  through  the  obstruction  that  held  it,  and  was  partially 
drained.  In  recent  years  an  artificial  dam  has  been  placed  in 
the  opening,  which,  when  in  repair,  causes  the  lake  above  to  ex- 
pand. During  summer  seasons  Humboldt  Lake  seldom  over- 
flows, and  is  then  the  lower  limit  of  the  drainage  system  of  the 
river  from  which  it  takers  its  name ;  but  in  winter  and  spring  the 
waters  escape  southwai-d,  and  spread  out  on  the  desert  so  as  to 
form  a  shallow  water  sheet,  known  as  Mirage  Lake.  Farther 
southward,  on  the  northern  part  of  Carson  Desert,  the  water 


INCLOSED   PERENNI.U.   LAKES.  113 

again  expands,  and  foi'nis  the  principal  source  of  North  Cai'son 
Lake,  ah-eady  described. 

In  the  summer  of  1882,  when  examined  by  the  ■writer,  Hi;m- 
l)oldt  Lake  covered  an  area  of  about  20  square  miles,  and 
did  not  overflow.  Its  waters  were  somewhat  alkaline,  owing  to 
evaporation  from  its  sm-faee  and  from  the  river  feetling  it.  Its 
depth  was  aljout  12  feet  over  the  greater  part  of  its  area. 

The  aljiiormal  character  of  the  lakes  of  Nevada,  as  would 
appear  to  a  visitor  from  lands  enjojdng  a  more  humid  climate, 
is  shown  by  the  fact,  that,  with  the  exception  of  moimtain  tarns, 
there  are  only  two  lakes  Ijelonging  to  the  class  normal  to  regions 
of  abundant  rainfall.  Of  these,  one  is  but  partly  in  Nevada 
and  at  a  high  elevation  among  mountains,  and  the  other  over- 
flows only  during  the  rainy  season,  and,  if  its  natural  discharge 
had  not  been  obstructed,  might  possibl}'  be  included  among 
ephemeral  lakes. 

Inclosed  Lakes. — The  lakes  of  Nevada  which,  next  to  the 
playa  lakes,  best  iUustrate  the  climatic  conditions  thei-e  prevail- 
ing, are  the  perennial  lakes  that  do  not  overflow.  Here  again 
the  list  is  short.  The  only  examples  that  can  be  found  are  Pyr- 
amid, Winnemueca,  and  Walker  lakes.  The  characteristics  of 
these  lakes  are  of  interest  not  only  in  the  study  of  the  present 
geography,  but  because  they  form  a  supplementary  chapter  to 
the  history  of  Lake  Lahontan,  which  occupied  the  same  I'egion 
at  a  comparatively  recent  date. 

Pi/ramid  and  Winnemueca  Lakes. — The  Truekee  Rivei-,  as 
already  stated,  discharges  into  both  Pyramid  and  Wiinienuicca 
lakes.  On  reaching  the  valley  in  Avhich  these  lakes  are  situated, 
the  river  divides  in  much  the  same  manner  as  many  streams 
send  off  distriljutaries  on  flowing  over  their  delta.  The  propor- 
tion of  water  reaching  either  lake  is  variable,  and  depends  on 
the  nature  of  the  obstruction  formed  in  the  channels  of  the 
river  below  whei-e  it  divides.  At  times  the  entire  supply  goes 
to  a  single  lake,  and  occasionally  one  lake  Ijecomes  trilnitary 
to  the  other.  The  lakes  are  siibjected  to  fluctuations  from  this 
cause,  as  well  as  from  variations  in  climatic  conditions. 

The  accompanying  map  of  Pyramid  and  Winnemueca  lakes 
(Plate  II. ),  made  in  1882,  will  obviate  the  necessitj'-  of  a  descrip- 
tion of  their  more  pronounced  features. 

Pyi-amid  Lake  was  first  made  known  to  civilized  man  by  Gen- 
eral Fremont,  who  traversed  its  eastern  shore  in  1844,  and  named 


lU 


PRESENT  XSD   EXTINCT  LAKES   OF  NEVADA. 


it  ill  reference  to  the  peculiar  form  of  an  island  near  its  southern 
end.  This  island,  as  may  be  seen  from  the  accompanying:  ilhis- 
tration,  has  a  remarkable  resemblance  to  one  of  the  I'yramids  of 
Egyi't. 


Pyi-aiiiiil  Islaiul,  P_%Taiiii(l  Lake,  Nevada. 

The  lake  has  a  length  of  :)()  miles,  and  near  its  northei-n  end 
is  12  miles  broad.  Its  area  in  September,  1882,  was  828  square 
miles.  Wiiiiiemucea  Lake  at  the  same  date  was  29  miles  long, 
with  an  average  ])readth  of  3i  miles,  and  an  api)roximate  area 
of  91  square  miles. 

The  sub-lacnsti-al  contours  given  on  the  map  (Plate  II.)  indi- 
cate, that,  if  the  waters  'of  these  lakes  were  withdrawn,  the 
basins  they  occupy  would  have  api)roximately  the  same  charac- 
teristics as  may  be  observed  in  many  adjacent  valleys  in  which 
playas  occupy  the  lowest  depressions.      This  fact,  together  with 


INCLOSED   PERENNIAL  LAKES.  115 

others  that  will  be  mentioued  later,  suggests  that  even  these 
broad  lakes  were  formerly  reduced  to  the  condition  at  present 
illustrated  l)y  niauy  eiihemeral  lakes. 

The  waters  of  both  Pyramid  and  Wiunemucca  lakes  are 
saline  and  alkaline.  The  chemical  composition  of  the  matter  in 
solution  is  shown  in  the  table  on  p.  117.  Like  all  inclosed  lakes, 
they  are  sensitive  to  climatic  changes,  and  exhibit  Ijoth  seasonal 
and  secular  variations.  They  record  the  net  balance  between  rain- 
fall and  evaporation,  and  rise  and  fall  with  changes  of  humidity 
nuich  as  a  liarometer  fluctuates  with  variations  in  atmosplici-ic 
pressure.  This  fa<'t  is  the  more  apparent,  since  the  lakes  receive 
scarcely  any  water  supply  from  other  sources  than  the  Truckee 
River.  The  springs  tributary  to  them  are  few  in  number  and 
small  in  volume.  The  rain  falling  on  the  adjacent  land  can  be 
safely  assumed  as  not  exceeding  five  inches  annually,  and  is  so 
distributed  that  it  is  mostly  absorbed  by  the  pai'ched  soil,  or 
evaporated,  liefore  it  can  gather  in  rills  and  find  its  way  to  the 
lakes. 

Much  might  be  said  of  the  rugged  [>icturesqueness  of  the 
mountains  aljout  these  dead  seas,  of  the  peculiar  islands  bivak- 
ing  their  surfaces,  of  their  abundant  fish  life,  of  the  varying 
tints  of  their  waters,  and  of  the  manner  in  which  carbonate  of 
lime  is  being  eliminated  from  them  through  the  agency  of  low 
forms  of  plant  life;  l)ut  space  will  not  jtermit. 

]\^(ilkei-  Lake.  —  This  lake,  likt^  the  two  just  described,  is  fed 
almost  entirely  l)y  the  snow  and  I'ain  falling  on  the  Sierra 
Nevada.  The  immediate  source  of  supply  is  Walker  River. 
Surveys  made  in  1SS2,  from  which  the  map  forming  Plate  111. 
was  constructed,  showed  that  Walker  Lak(^  was  then  25|  miles 
long  from  north  to  south,  and  had  an  average  breadth  of 
between  4^  and  5  miles.  Its  area-  Avas  about  9.j  sijuare  miles. 
The  greatest  depth  oljtained  by  such  soundings  as  it  was  iH'ac- 
ticable  to  make  was  225  feet.  The  waters  are  alkaline  and  unfit 
for  human  use,  although  drunk  by  animals.  The  chemical  com- 
position is  given  on  p.  117. 

The  west  shore  of  Walker  Lake  is  bordered  l)y  a  precipitous 
mountain  range,  which  rises  from  the  water's  edge  so  abruptly 
that  not  room  enough  for  even  a  bridle  path  intervenes.  This 
mountain  ridge  is  the  uptiu'ned  bordei-  of  a  tilted  block  of  the 
earth's  crust,  and  is  bounded  on  tlie  (Hist  by  a  ]irofound  fracture. 
The  Ijlock  on  the  east  side  of  the  fracture  has  sul)sided  with 


ll(j  PRESENT  AND   EXTINCT  L.UCES   OF   NEVADA. 

reference  to  the  west  side,  and  the  depression  thus  formed  is  oc- 
cupied by  the  present  lake.  Like  many  of  the  valleys  of  Nevada, 
this  is  a  typical  fault  liasin.  The  exceptional  depth  of  tlie  lake  is 
probably  due  to  recent  movements  of  the  fault  that  gave  it  origin. 

Crater  Lakes. — On  the  western  side  of  Carson  Desert  there 
are  two  circular  depressions  Avith  elevated  rims  that  are  filled 
with  intensely  alkaline  water.  These  are  known  as  Soda  Lakes, 
and,  from  their  proximity  to  a  former  settlement  called  Rag- 
town,  are  sometimes  designated  as  the  "Ragtown  Ponds."  The 
larger  lake  has  an  area  of  298i  acres;  and  the  smaller  is  a  pond 
of  varia1)le  size,  much  modified  in  recent  years  by  excavations. 
The  rim  of  the  larger  lake  in  its  highest  part  rises  80  feet  above 
the  surrounding  desert,  and  is  165  feet  above  the  lake  it  incloses. 
The  outer  slope  of  the  rim  is  gentle,  and  merges  imperceptibly 
into  the  surface  of  the  surrounding  desert;  but  its  inner  slope 
is  abrupt  and  in  places  precipitous.  A  series  of  careful  sound- 
ings made  in  the  lake  show  its  maxinnim  depth  to  be  147  feet. 
The  total  dei)th  of  the  depression  is  therefore  '212  feet. 

This  great  hole  in  a  nearly  level  plain,  as  shown  by  the  struc- 
ture of  its  walls  and  the  nature  of  the  material  composing  them, 
is  of  volcanic  origin.  It  is  a  volcanic  crater  from  which  dust, 
lapilli,  and  bombs  a  foot  or  two  in  diameter,  have  been  Aiolently 
ejected,  but  which  did  not  pour  out  liquid  lava.  The  diameter 
of  the  crater  from  opjiosite  jioiuts  in  its  rim  varies  from  a  mile  and 
a  half  to  two  miles.  This  volcano  is  situated  in  the  basin  formerly 
flooded  by  Lake  Lahontan,  and  was  in  activity  before  that  lake 
disapi)eai-ed,  as  well  as  at  a  later  date.  The  waters  now  occupy- 
ing the  crater  find  their  way  to  it  by  percolating  throiigh  the  thick 
lake  beds  that  floor  the  Carson  Desert,  and  owe  their  high  per- 
centage of  saline  matter  to  the  salts  dissolved  from  the  rocks 
through  which  they  find  their  way. 

The  8oda  Lakes  are  the  basis  of  a  considerable  industry  in 
carbonate  and  bicarbonate  of  soda.  The  various  salts  they  con- 
tain are  indicated  in  the  table  on  p.  117.  These  lakes  are  excep- 
tional in  character,  and  have  but  slight  bearing  on  the  study  of 
climatic  change  from  which  most  of  the  lakes  of  Nevada  derive 
their  chief  interest. 

Analyses  of  Lake  Watei!s. — In  order  to  com])lete  an  out- 
line of  the  data  now  availaljle  concerning  the  existing  lakes  of 
Nevada,  the  following  table,  showing  the  chemical  composition 
of  the  matter  in  solution  in  then-  waters,  is  here  inserted.    Analy- 


SUMMARY   OF   PRESENT  LAKES. 


ii; 


ses  of  two  saline  aud  alkaline  lakes  in  the  regions  adjacent  to 
Nevada  are  also  presented  for  comparison. 

Analyses  of  the  Wtiters  of  Lakes  in  the  Arid  lieijion^  (Parts  in  1,000). 


ComtituentSL 

Abert 

Lake. 

Oregon.^ 

Great 

Salt  Lake, 
ntab. 
(1860.) 

49.090 

2.407 

.2.55 

3.780 

83.946 

9.858 
Trace. 

Huraboldt 

Lake, 
Nevada. 

.27842 
.00083 
.01257 
.01648 
.29545 
.20120 
.03040 
.00069 
Trace. 
.03250 

hnda  Lake, 
Nevada. 

Pyramfd 
Lake. 
Nevada. 

Walker 

Lake. 

Nevada. 

Wlnne-    i      Lake 
murca        Takue, 
Lake.       California- 
Nevada.       Nevada. 

boiliuiii  (Na) 

Potassium  (K)      .... 

Calcium  (Ca) 

Magnesium  (Mg)  .... 

Chlorine  (CI) 

Carbonic  acid  (CO;))      .     . 
Sulphuric  acid  (^04)     .     . 
Pliosiihoric  acid  (Ill'll4)   . 
Boracic  acid  (13407)     .     . 

Silica  (SiO.2) 

Hydrogen  (in  bicarbonates) 

14.245 
.621 

13.055 

9.199 

.685 

.224 
.050 

40.919 
2.357 

.^45 
40.851 
10.858 
11.857 

.286 
.278 

1.1796 
.0733 
.0089 
.0797 

1.4300 
.4990 
.1822 

.0334 

.85535 
Trace. 
.02215 
.038.30 
.58375 
.47446 
.52000 

.00760 

1.2970 
.0686 
.0196 
.0173 

1.6934 
.3458 
.1333 

.0275 

.0073 
.0033 
.0093 
.0030 
.0023 
.0287 
.0054 

.0137 

37.985 

149.930 

.92860 

113.651 

3.4861 

2.50160 

3.6025 

.0730 

1  Compiled  principally  from  Table  C,  in  U.  S.  Geological  Survey  Monograph,  vol.  xi. 

2  Analyses  by  T.  M.  Cliatard,  x\merican  Journal  of  Science,  ser.  3,  vol.  xxxvij.,  1888,  pp.  146-160. 

The  analysis  of  the  water  of  Lake  Tahoe  shows  that  it  is  of 
gi'eater  purity  tlian  the  average  of  fresh-water  lakes  and  streams. 

SuMMAiiY  RESPECTING  THE  ExisTiN(;  Lakes. — As  may  be  seeu 
from  a  glance  at  a  map  of  Nevada,  all  the  larger  lakes  that 
diversify  her  surface  are  near  the  western  border,  and  are  sup- 
plied by  precipitation  on  the  Sierra  Nevada.  Hundreds  of 
basins,  some  of  them  scores  and  even  Imndreds  of  stpiare  miles 
in  area,  and  so  inclosed  as  to  be  suitable  for  holding  broad  lakes, 
exist  throughout  the  State,  liut  the  aridity  of  the  region  pre- 
cludes their  being  occupied  by  perennial  water  liodies.  In  many 
instances  the  annual  rainfall  in  these  desert  basins  is  so  meager 
that  it  is  at  once  absorbed  by  the  thirsty  soil,  or  returned  to  the 
atmosphere  as  vapor,  and  not  even  ephemeral  lakes  are  formed. 
This  is  especially  true  of  the  southern  portion  of  the  State, 
where  no  lakes  occur  except  a  few  pools  fed  principally  by  fis- 
sure springs. 

Should  the  Grreat  Basin,  as  the  ai-ea  of  intei'ior  drainage 
between  the  Sierra  Nevada  and  Wasatch  Mountains  is  termed, 
experience  a  change  of  climate  of  such  a  nature  that  the  rain- 
fall would  be  increased  or  evaporation  dimiiiislied,  the  most 
obvious  result  would  lie  the  appearance  of  lakes  in  valleys 
that  are  now  either  dry  tliroughont  the  year  (»■  hold  playa 
lakes,  and  the  expansion  of  the  perennial  lakes.     The  lakes 


118        PRESENT  AND  EXTINCT  LAKES  OF  NEVADA. 

uow  supplied  liy  streams  from  the  Sierra  Nevada,  and  the 
niueh  smaller  lakes  at  the  base  of  the  East  Humboldt  Mouii- 
taius,  would  expaud,  and  invade  the  adjacent  valleys  until  they 
exposed  sufficient  surface  to  the  atmosphere  to  counterbalance 
the  inflow  by  evaporation.  If  before  this  stage  was  reached  a 
lake  rose  sufficiently  to  find  an  outlet,  it  would  overflow,  and 
become  tributary  to  some  lower  basin.  The  manner  in  which 
the  present  perennial  lakes  fluctuate,  and  the  appeai'anee  and 
vanishiniT  of  playa  lakes  from  season  to  season  or  in  response 
to  climatic  oscillations  ha\"ing  a  longer  term,  suggest  that  only 
moderate  climatic  changes  of  the  nature  above  indicated  would 
be  requii'ed  to  prodiice  marked  results  in  the  appearance  of  the 
basins  of  Nevada. 

The  study  of  the  surface  geology  of  the  Great  Basin  has 
shown  that  a  climatic  change  of  the  natm-e  just  suggested  did 
occur  at  a  time  not  remote.  The  streams  from  the  mountains 
increased  in  volume ;  many  channels  were  occupied  by  flowing 
water  that  are  now  dry  throughout  the  year ;  lakes  ai)peared  in 
many  and  probably  in  all  of  the  inclosed  basins  that  are  now 
arid ;  the  perennial  water  liodies  expanded  until  they  became 
veritable  inland  seas.  The  records  of  the  time  when  Nevada 
was  a  lake  I'egion  are  fresh  and  easily  read.  Let  us  see  what 
thoughts  their  study  will  suggest. 

EXTINCT   LAKES. 

Intimately  associated  with  the  lakes  in  the  valleys  of  Nevada, 
referred  to  above,  are  the  records  of  glaciers  on  the  Sieri'a 
Nevada,  East  Humboldt,  and  other  mountains.  For  this  and 
other  reasons  the  extinct  lakes  here  considered  are  referred 
to  the  Pleistocene  division  of  the  earth's  history,  or  the  time 
immediately  preceding  and  merging  into  the  time  of  man. 

Pleistihexe  Lakes. — Many  valleys,  of  Nevada  might  be  enu- 
merated which  were  occupied  by  lakes  i>revious  to-the  present 
time  of  aridity.  There  is  probaljly  not  an  inclosed  basin  in 
the  State  but  what  had  its  lake  during  Pleistocene  times.  What 
is  now  in  great  part  a  desert  land  was  then  a  lake  region  with 
as  gi'eat  a  water  surface,  in  reference  to  its  area,  as  the  pi-esent 
lake  region  of  central  New  York  or  of  northern  England.  Unlike 
many  lake  regions  at  the  present  day,  however,  a  large  number 
of  these  ancient  water  bodies  did  not  overflow,  and  at  times  at 


EXTINCT  LAKES.  Hi) 

least  were  saline  aud  alkaline.  The  configuration  of  the  land 
was  such  as  to  lead  to  the  existence  of  two  gi'eat  inland  seas 
that  outranked  their  neighbors,  the  histories  of  which  are  of 
unusual  interest. 

One  of  these  seas,  named  Lake  Bonneville,  occupied  Salt 
Lake  valley,  Utah,  and  several  depressions  opening  from  it,  and 
was  supplied  mainly  Ijy  streams  flowing  westward  from  the 
Wasatch  Mountains.  A  contemporary  lake,  called  Lake  Lahou- 
tan,  situated  in  northwestern  Nevada,  and  extending  into  Cali- 
fornia, was  supplied  principally  l)y  streams  flowing  eastward 
from  the  Sierra  Nevada.  Lake  Bonneville  was  the  larger  and 
deeper,  and  overflowed.  Lake  Lahontan,  on  the  other  hand, 
never  overflowed.  Owing  to  the  absence  of  an  outlet,  it  imder- 
went  many  fluctuations  in  vohmie  aud  composition,  and  left 
the  most  interesting  and  instructive  chemical  records  of  any 
lake  known.  Lake  Lahontan  was  886  feet  deep  in  the  deepest 
part,  had  an  area  of  8,422  square  miles,  and  received  the  rainfall 
of  40,000  scpiare  miles. 

The  regions  draining  to  these  two  great  la-kes  occupied  the 
entire  space  between  the  Wasatch  Mountains  and  the  Sierra 
Nevada,  and  for  a  distance  of  2.')  miles  near  the  northern  pai-t 
of  the  Utah-Nevada  boundary  their  hydrographic  l)asins  had  a 
divide  in  common.  The  smaller  Pleistocene  lakes  at  the  base  of 
the  East  Humboldt  Mountains,  previously  mentioned,  were  situ- 
ated to  the  south  of  these  two  drainage  areas. 

Lake  Lahontan. — Should  a  climatic  change  occur  of  such  a 
mxture  that  it  would  allow  Pyramid,  Winnemucca,  and  Walker 
lakes  to  expand  until  they  became  confluent  and  invaded  manj'' 
adjacent  valleys,  and  continued  to  increase  in  depth  until  the 
sounding  line  in  the  deepest  part  showed  886  feet  of  water,  the 
appearance  of  Lake  Lahontan  at  its  highest  stage  would  bo  prac- 
ti(_"a.lly  restored. 

Tlie  outline  of  th(^  lake  is  indicated  on  Plate  I.,  from  which 
the  valleys  it  occupied,  and  the  extreme  irregularity  of  its  out- 
line, may  be  ascertained  at  a  glance.  One  of  the  peculiar  geo- 
graphic features  is  that  the  lake  surrounded  a  large,  irregular 
island,  on  which  there  was  a  smaller  lake.  So  far  as  knoAvu, 
this  island  lake  did  not  OA-(M-flow.  A  broad  playa  now  mai'ks 
its  site. 

The  records  left  by  Lake  Lahontan  during  its  various  flu(,'tua- 
tions  may  be  groiiped  in  two  main  classes,  physical  and  chemical. 


1'20  PRESENT   AND   EXTINCT   LAKES   OF   NEVADA. 

The  Physical  Eecoeds. — The  vim  of  the  Lahoutau  bashi 
has  beeu  traced  throughout  its  entire  extent,  and  found  to  be 
unbroken  by  a  channel  of  overflow.  The  water  body  it  held 
was  therefore  an  inclosed  lake,  and,  like  others  of  its  class,  must 
have  been  subject  to  repeated  fluctuations  of  level.  That  such 
was  its  history,  is  also  e%-ident  from  the  multitude  of  teiraces 
still  remaining  as  records  of  its  changes.  In  this  as  in  all 
abandoned  lake  basins,  the  elements  of  shore  toi)Ograi>hy  to 
which  we  turn  for  a  large  pai't  of  the  history  of  the  vanished 
waters  are  terraces,  sea  cliffs,  emliankments,  and  deltas. 

Terraces  and  Sea  C/(//k — The  most  common  of  the  records 
inscribed  on  the  borders  of  the  Lahontan  basin  are  wave-cut 
ten-aces.  These  may  be  traced  through  a  large  portion  of  the 
basin,  but  are  most  distinct  on  the  liorders  of  the  larger  deserts. 

In  traveling  over  the  Central  Pacific  Railroad  between  Gol- 
conda  and  Wadsworth,  one  is  seldom  out  of  sight  of  the  long 
horizontal  lines  drawn  by  the  waves  of  the  ancient  lake  on  the 
shores  that  confined  them.  Eecords  of  the  same  character  may 
be  traced  continuously  about  the  borders  of  the  Black  Rock 
and  Smoke  Creek  deserts,  and  are  strongly  defined  along  the 
bases  of  the  mountains  overlooking  Pyramid  and  Winnemucca 
lakes.  They  are  again  plainly  legil  >le  on  the  steep  slopes  Vior- 
dering  Walker  Lake,  as  may  be  obsex-ved  by  the  traveler  over 
the  Carson  and  Colorado  Railroad. 

The  highest  of  these  numerous  shore  lines  has  been  named 
the  Lahontan  Beach,  as  it  records  the  highest  water  stage  of  the 
former  lake.  Its  elevation  above  the  sea  is  4,343  fee  at  Mill 
City,  and  from  4,418  to  4,4*27  feet  at  the  loAver  end  of  Humboldt 
Lake.  These  measurements,  together  with  many  others,  show 
that  the  old  beach  is  not  now  honzontfd.  Movements  have 
taken  place  principally  along  numerous  fault  lines,  and  the 
relief  is  not  now  precisely  the  same  as  when  the  old  lake  existed. 
An  average  of  the  various  measurements  indicates  that  the  pres- 
ent elevation  of  the  Lahontan  Beach  is  about  4,378  feet  above 
the  sea.  This  is  the  nearest  ajiproximation  we  can  make  to  its 
original  altitude. 

Besides  the  Lahontan  Beach,  there  are  three  other  water 
lines  of  sufficient  importance  in  the  history  of  the  lake  to  de- 
serve special  designation.  One  of  these  is  a  strongly  defined 
terrace  30  feet  below  the  Lahontan  Beach,  and  at  the  upper 
limit  of  a  calcareous  deposit  precipitated  from  the  waters  of  the 


TEKEACES   OF   LAKE   LAHONTAN. 


121 


ancient  lake,  and  described  later,  whit-li  has  been  named  litlwid 
tufa.  This,  thei-efove,  is  called  the  Lithokl  Terrace.  Its  eleva- 
tion is  50(J  feet  above  the  1882  level  of  Pyramid  Lake,  which  was 
then  3,783  feet  above  sea  level. 

Another  chemical  deposit,  known  as  dendritic  tufa,  occurs  in 
great  quantities  in  the  same  basin.  At  its  upper  limit  it  is 
bounded  by  a  water  line,  usually  but  poorly  defined,  named  the 
Bt'iidrific  Terrace.  Its  elevation  is  320  feet  above  the  datum 
plain  just  mentioned. 

Between  the  Dendritic  Terrace  and  the  surface  of  Pyramid 
Lake  there  is  a  broad  platform,  which  is  the  strongest  and  best 


Fwrt 

Laliniitin  Beach . .  530 
l.iihiiiilTerrai-f...  50O 


UcMilritic  Ti-rnii-i'.  S->0 

^t^<.ii.i»ttfys^^ ■  Thinolite  Terraco.  110 

^^,_,^.     — __  rSurfai'e    of    Pvni- 

^^^  mill  LakL-(lss-.>).  0 


Generalized  Profile  of  Lahontaii  Shores. 


defined  of  all  the  Lahontan  water  lines.  It  marks  the  upper 
limit  of  a  third  variety  of  tufa,  known  as  thii/olife,  and  is  there- 
fore called  the  ThhioJitc  Terrace.  Its  elevation  is  about  110  feet 
above  the  level  of  Pyramid  Lake  in  1882.  This  terrace  has  T)eeu 
found  to  extend  entirely  ai'ound  the  valleys  occui)ied  by  Pyra- 
mid and  Winnemucea  lakes,  and  may  also  be  followed,  though 
less  distinctly,  about  the  borders  of  Black  Rock,  Smoke  Creek, 
and  Carson  deserts. 

The  terraces  just  named,  together  with  the  1882  level  of 
Pyramid  Lake,  furnish  four  definite  horizons  that  will  be  found 
cohvenient  reference  plains  in  tracing  the  Pleistocene  history 
of  the  basin.  It  is  only  at  exceptional  localities,  however,  that 
these  terraces  can  be  followed  for  any  cousideraVjle  distance,  and 
at  only  a  few  points  could  a  sequence  like  the  one  shown  above 
be  obtained.  The  relative  age  of  the  various  water  lines  indi- 
cated in  the  diagram  will  be  discussed  when  the  chemical  history 
of  the  lake  is  considered. 


12'2        PRESENT  AND  EXTINCT  LAKES  OF  NEVADA. 

The  highest  terrace  of  all,  the  Lahoutau,  is  au  iueouspicuous 
feature  iu  itself,  but  it  is  important  as  forming  the  boundary 
between  subaorial  and  subaqueous  sculpture  on  the  sides  of  the 
valleys.  It  usually  appears  as  a  terrace  of  construction  a  few 
feet  wide,  resting  on  the  broad  Lithoid  Terrace  30  feet  below. 

Besides  the  more  definite  and  strongly  marked  terraces  to 
which  names  have  been  given,  there  are  a  large  number  of  less 
deeply  engraved  lines  on  nearly  every  portion  of  the  fonuer 
shore.  Each  of  these  scorings  is  the  reeoi-d  of  a  pause  in  the 
fluctuations  of  the  water  surface.  Collectively  they  indicate 
numerous  changes  in  the  lake  level.  The  obscurity  and  want 
of  strength  in  many  of  them  are  no  doubt  due  in  a  great  meas- 
ure to  the  fact  that  the  slopes  on  which  they  were  traced  have 
been  brought  within  the  reach  of  wave  action  many  times.  In 
this  way  the  i-ecords  first  made  have  been  erased  or  obscured  by 
subsequent  additions. 

Bars  (1)1(1  Enihdi/Jciiienfs. — At  many  localities  in  the  Lahontan 
basin  there  are  extensive  embankments  of  gravel  and  sand  de- 
rived from  the  cutting  of  some  of  the  terraces  just  referred  to. 

An  instructive  example  of  the  constructive  action  of  the  waves 
and  evirrents  is  shown  on  the  map  forming  Plate  IV.,  of  the  gi'eat 
gi'avel  embankment  now  retaining  Humboldt  Lake.  The  map 
referred  to  is  from  plane-table  sm'veys  made  by  Mr,  Willard  D. 
Johnson  of  the  I".  S.  Geological  Sm-vey,  and  is  so  graphic  that 
it  requires  but  little  interpretation. 

As  previously  stated,  Humboldt  Lake  owes  its  existence  to 
the  damming  of  the  river  tributary  to  it  by  extensive  gi-avel 
embankments  which  were  thrown  completely  across  its  channel 
during  the  time  that  Lake  Lahontan  occupied  the  valley.  The 
highest  level  of  the  ancient  water  smface  is  represented  on  the 
map  by  a  heavy  l)roken  line,  and  appears  in  the  topography  of 
the  countrj'  as  a  gravel  embankment,  or  as  a  wave-cut  terrace 
at  the  base  of  a  sea  clitf  sometimes  a  hundred  feet  in  height. 

The  valley  in  which  Humboldt  Lake  is  situated  was  a  strait 
at  the  time  of  the  higher  stages  of  Lake  Lahontan,  and  con- 
nected the  Carson  body  of  the  former  lake  with  the  waters  that 
occupied  the  northern  part  of  the  Humboldt  valley.  At  a  late 
stage  in  the  ancient  lake  an  embankment  of  gravel  from  50  to 
12")  feet  in  height  was  carried  completely  across  the  valley  iu 
such  a  manner  as  to  suggest  that  it  is  au  artificial  structure 
intended  to  confine  the  drainage.     At  either  end  the  main  em- 


BAKS   AND   SEDIMENTS   OF   LAKE   LAHONTAN.  123 

baukment  ■widens  as  it  approaches  the  shore,  aud  forms  hoa\y 
triaiigiahxr  masses  of  gi'avel,  on  the  surface  of  which  appear 
many  smaller  bars  built  of  clean,  well-worn  shingle.  These 
secondary  bars  form  ridges  with  rounded  crests,  fi-om  a  few 
feet  to  30  or  40  feet  in  height,  and  ueai-ly  level-topped  foi-  long 
distances.  These  are  seldom  straight,  l)ut  curve  with  beautiful 
symmetry,  each  gracefully  bending  ridge  marking  the  course  of  a 
current  in  the  waters  of  the  ancient  lake  in  which  it  was  formed. 

The  embankment  crossing  the  valley  declines  gently  in  height 
from  either  end  toward  the  center,  and  has  been  cut  through 
at  its  lowest  point  by  the  overflow  of  Humljoldt  Lake.  The 
gap  carved  by  the  outflowing  waters  is  shown  in  the  profile  at 
the  bottom  of  Plate  IV.  The  diagi-am  was  constructed  from  a 
line  of  levels  run  from  the  Lahontan  Beach  on  the  Niter  Buttes 
to  the  highest  water  line  on  the  west  side  of  the  vallej'. 

At  many  other  localities  about  the  abandoned  shores  there 
are  fine  examples  of  gi'avel  bars  and  embankments  which  show 
many  details,  and  serve  as  records  of  fluctuations  and  of  changes 
in  the  direction  of  the  shore  currents  in  the  old  lake. 

Sediments. — The  tril)utaries  of  lakes,  disregarding  organic 
substances,  contain  two  classes  of  iminirities :  (a)  minei-al  mat- 
ter in  suspension,  and  {/>)  mineral  matter  in  solution. 

Besides  holding  fine  silt  in  suspension,  streams  also  roll  peb- 
bles aud  stones  along  their  beds.  On  entering  a  lake,  all  tliis 
material  subsides  more  or  less  quickly,  forming  lake  beds,  gravel 
deposits,  etc.  In  the  sedimentation  of  lakes,  the  coarser  and 
heavier  debris  is  invariably  di-opjied  near  shore,  while  the  finer 
and  lighter  suljstances  are  floated  to  a  greater  distance  befoi-e 
suljsiding.  In  this  mannei"  coarse  shore  and  fine  ofl'sliore  de- 
posits originate. 

The  sedimentary  deposits  of  Lake  Lahontan  exhiVdt  three 
definite  divisions :  viz.,  upper  lacustral  clays,  from  50  to  75  feet 
thick ;  medial  gi'avels,  from  50  to  200  feet  thick ;  lower  lacustral 
clays,  not  fully  exposed,  but  at  least  100  feet  thick.  A^^lerever 
any  considerable  section  of  Lahontan  sediment  is  seen,  these 
three  divisions  appear  in  unvarying  sequence. 

The  upper  and  lower  members  of  the  series  are  composed  of 
marly  days,  which  show  by  their  fineness,  and  the  evenness  of 
their  lamination,  that  they  were  depo.sited  in  deep  still  water. 
The  middle  member,  on  the  other  hand,  usually  consists  of  well- 
rounded  gravel  and  sand,  in  some  instances  becoming  coarse, 


« 


1:24  TRESEXT   AND   EXTINCT  LAKES   OF   NEVADA. 

aud  including  bowlders  a  foot  or  more  iu  diameter.  This  deposit 
is  current-bedded,  aud  exhibits  many  variations,  indicating  that 
it  was  deposited  in  shallow  water. 

The  interpretation  of  this  section  gives  an  outline  of  the  later 
Pleistocene  history  of  the  Lahoutan  basin.  There  were  two  high- 
Avater  periods  during  which  tine  clays  were  deposited.  Separat- 
ing tliese,  there  was  a  time  when  the  lake  was  low,  and  allowed 
current-borne  gi-avels  to  be  carried  far  out  over  the  previously 
formed  lake  beds.  During  the  second  flooding  especially,  the 
waters  underwent  long  concentration,  and  at  certain  stages 
deposited  vast  ipuuitities  of  tufa;  during  this  stage,  also,  the 
lake  received  large  quantities  of  pumiceous  dust,  thrown  out 
by  volcanoes  in  violent  eruption.  The  secoml  rise  of  the  lake 
was  followed  by  the  present  period  of  desiccation,  which  wit- 
nessed the  evajioration  of  its  waters,  and  the  exposure  of  its 
sediments  to  subaerial  erosion.  The  rivers,  in  flowing  across 
the  exposed  lake  beds,  carved  the  deep  channels  we  have  de- 
scribed, and  are  now  spreading  stream-  and  current-borne 
gi'avels  far  out  in  the  central  portions  of  the  valleys,  thus  in 
nniny  ways  repeating  the  conditions  that  characterized  the  time 
during  which  the  medial  gravels  were  deposited. 

The  Chemical  Records. — Lake  Lahoutan  belonged  to  the 
class  of  inclosed  lakes  of  which  the  Dead  Sea,  Caspian  Sea,  and 
Great  Salt,  Mono,  Pyramid,  Walker,  Winnennicca  lakes,  etc., 
are  existing  examples.  Lakes  of  this  class  are  supplied  mainly 
by  streams  in  the  same  manner  as  the  far  more  numerous  class 
of  lakes  with  outlets,  l)ut  the  inflow  is  counterbalanced  solely  by 
evaporation. 

The  waters  of  streams  and  springs  are  never  chemically  pure, 
but  contain  mineral  matter,  such  as  carbonate  of  lime,  common 
salt,  etc.,  in  solution.  As  evaporation  takes  i>lace  from  the  sur- 
face of  an  inclosed  lake  to  which  such  waters  are  contributed, 
the  relative  amount  of  saline  matter  it  holds  is  inci'eased  until  the 
point  of  saturation  for  one  or  more  of  the  contained  salts  is  reached 
and  precipitation  begins.  Changes  of  temperature  aud  the  vital 
action  of  plants  aud  animals  may  retard  or  hasten  the  time  when 
some  of  the  salts  liegin  to  be  eliminated ;  but,  in  general,  con- 
centration continues,  if  the  life  of  the  lake  is  sufficiently  pro- 
longed, until  the  once  sweet  and  wholesome  waters  become 
dense  brines.  In  the  Dead  Sea,  for  example,  the  total  solids  in 
solution  amount  to  about  24  per  cent ;  tliat  is,  about  one  fourth 


CHEMICAL   DEPOSITS.  1'2.") 

the  weight  of  a  given  vohime  of  the  l)rine  is  due  to  material 
held  iu  sokitioii.  Oceau  water  contains  about  3.5  per  cent  of 
saline  matter.  These  may  be  called  "standard  l)rines,''  with 
which  interesting  comparisons  may  be  made  of  the  analyses  of 
the  water  of  the  present  lakes  of  Nevada  already  given. 

The  principal  streams  tril)utaiy  to  Lake  Lahontaii  occupied 
the  same  channels  through  which  Carson,  Walker,  and  Truckee 
rivers  now  flow.  It  is  safe  to  assume  tliat  the  chemical  com- 
position of  the  waters  <lischarged  tlirough  these  channels  at 
the  present  time  is  a  fair  api>roximatiou  to  the  comiiosition  of  the 
streams  that  emptied  into  the  old  lake,  exce^jtiug  that,  when  the 
precipitation  was  more  abundant  than  at  present,  the  percent- 
age of  saline  matter  iu  solution  was  somewhat  less  than  is  now 
carried.  Analyses  have  shown  that  the  waters  at  present  tribu- 
tary to  the  Lahontan  basin  have  about  the  nonnal  composition 
of  surface  streams,  which,  as  found  from  analyses  of  a  large 
number  of  typical  rivers  in  lioth  America  and  Eurojic,  carry 
0.01888  per  cent  of  total  solids  in  solution,  of  which  one  half, 
or  0.00887  per  cent,  is  calcium  carbonate  (carbonate  of  liTue). 

As  Lake  Lahontan  never  rose  so  as  to  overflow,  all  of  the 
saline  matter  carried  into  it  uuist  still  remain  iu  its  l)asin. 

Calcarmns  Tufa.  —  The  traveler  who  crosses  the  dee2>er  valleys 
formerly  occupied  by  the  waters  of  Lake  Lahontan  cannot  fail 
to  have  his  attention  attracted  by  curious  and  frP(iuently  fan- 
tastic rock  masses,  the  like  of  which  is  seldom  seeu  elsewhere. 
These  strange  forms  rise  from  the  gi'ay  desert  like  huge  mush- 
rooms, or  iu  clustered  tower-like  structures  having  a  striking 
resemblance  to  half-ruined  castles.  They  vary  in  height  from  a 
few  feet  to  fully  a  hundred  feet,  and  not  infrequently  are  several 
hundred  feet  in  circumference.  Some  of  the  most  remarkable 
of  these  forms  occur  about  the  shores  of  Pyramid  and  Winne- 
mucca  lakes,  or  rise  from  their  bottoms,  and  form  uni<pi(>  islands. 
The  general  appearance  of  one  of  these  structures  is  sliowu  on 
p.  126.  The  reader  will  see  at  once  that  these  nearly  jierpeii- 
dieular  towers  with  rounded  dome-shaped  sumuiits  are  not  the 
result  of  erosion,  but  still  present  their  original  outlines. 

These  remai-kable  mushroom-shaped  and  castle-like  forms 
are  composed  of  calcium  carl)Oiuxte.  Tliey  owe  tlieir  origin  to 
the  precipitation  of  the  stony  matter  comp(»siHg  tliem  from  the 
waters  of  Lake  Lahontan.  In  geological  language,  this  rock  is 
calcareous  tufa. 


12(i 


I'KESENT   AND   EXTINCT   LAKES  OF   NEVADA. 


On  the  borders  of  tlie  deserts  that  were  formerly  flooded,  and 
on  the  hills  and  buttes  rising  with  them  and  once  existing  as 
islands,  there  are  vast  deposits  of  tnfa  which  sheathe  the  ancient 
shores  to  within  thirty  feet  of  the  highest  beach  line.  Tlie  thick- 
ness of  this  deposit  is  in  some  instances  upwards  of  eighty  feet. 


Tula  iiciHisils  on  liic  Sliorc  of  Pyramid  Lake. 

The  total  amount  of  these  rocks  of  cheinieal  origin  is  astonish- 
ingly great,  and  can  only  l)e  estimated  in  millions  of.  tons.  In 
no  other  known  instance  is  there  such  a  magnificent  display  of 
rocks  formed  l)y  precipitations  from  lake  waters. 

If  one  halts  in  his  journey  across  the  bed  of  the  ancient  sea 
of  Nevada,  and  examines  the  structure  of  the  tower-  and  castle- 
like forms  that  attract  his  attention,  very  interesting  facts  may 
be  observed. 


CAIiCAKEOUS  DEPOSITS.  V2l 

111  some  instauces  tliQ  towers  have  fallen,  and  sections  of 
their  interiors  are  revealed.  It  will  then  be  found  that  they 
were  l)uilt  up  hy  the  successive  deposition  of  layer  on  layer 
of  stone.  When  the  sections  are  approximately  circular,  these 
layers  appear  as  concentric  bands,  not  unlike  the  annual  rings 
in  the  trunk  of  an  oak,  but  frequently  they  are  several  inches 
and  even  two  or  three  feet  liroad.  It  will  also  be  noticed  that 
three  varieties  of  tufa  are  present,  and  that  each  variety  shows 
many  minor  subdivisions  marked  by  changes  in  structure,  color, 
etc.  As  one  proceeds  with  this  examination,  the  evidence 
becomes  conclusive  that  even  the  largest  of  the  water-built  cas- 
tles began  by  the  precipitation  of  carbonate  of  lime  about  a  solid 
nucleus,  and  grew  slowly  by  the  addition  of  successive  layers  of 
the  same  material.  The  manner  iu  which  these  deposits  wei-c 
formed,  and  the  astonishing  results  attained,  show  tliat  a  gi-cat 
lapse  of  time  was  required  for  the  process.  The  life  of  the  old 
lake  must  have  embraced  at  least  several  thousand  years. 

The  inner  core  of  the  tufa  towers,  and  the  tirst  layer  formed 
on  the  sides  of  the  basin,  consist  of  a  compact,  stony  variety  of 
tufa,  having  in  common  with  the  subsequent  deposits  a  yellowish 
color.  On  account  of  its  compact  texture,  this  lias  l)een  called 
Uthoid  iiifd.  Its  thickuess  in  many  instances  is  from  ten  to 
twelve  feet;  but,  as  it  is  usually  concealed  by  both  chemical 
and  mechanical  deposits  of  later  date,  its  maximum  thickness 
is  probably  not  known. 

Inclosing  the  Uthoid  tufa  in  the  towers  and  castles,  and  form- 
ing a  superimposed  layer  on  the  first  incrustation  sheathing  tln> 
cliffs,  is  a  second  variety  of  tufa  composed  of  rough  but  well- 
defined  crystals,  that  are  frequently  six  or  eight  inches  long,  and 
an  inch  or  more  in  diameter.  These  crystals  are  known  as  tli'm- 
olifr,  and  the  name  fJiiiioHfic  tufa  has  been  given  to  the  deposit 
of  which  they  formed  the  major  part.  The  thickness  of  this 
variety  is  from  six  to  eight  feet  at  its  upper  limit,  and  from  ten 
to  twelve  feet  at  the  lowest  horizon  exposed. 

Succeeding  the  thiiiolitic  tufa,  and  forming  the  most  abun- 
dant deposit  of  calcium  carbonate  in  the  basin,  is  a  third  pre- 
cipitate of  the  same  general  nature  as  those  just  mentioned,  but 
having  an  open,  branching  structure,  ami  strongly  resemltling  a 
mass  of  symmetrically  arraiigeil  twigs  changed  to  stone,  and  for 
this  reason  named  dendritic  tufa.  In  many  instances  this  deposit 
is  fully  sixty  feet  in  thickness. 


128  PBESEXT   .VXD   EXTINCT  LAKES   OF  NEVADA. 

The  vertical  rauge  of  these  three  varieties  of  tufa  varies  in 
au  interesting  manner.  Their  limit  above  the  1882  level  of  Pyr- 
amid Lake  is  shown  in  the  figure  on  p.  121,  where  the  horizou 
of  the  terrace  with  which  each  is  associated  is  intlicated. 

The  lithoid  tufa  extends  up  the  rocky  borders  of  the  valley 
500,  the  thinolitic  110,  and  the  dendritic  320,  feet  above  Pyramid 
Lake.  How  much  below  the  level  of  the  lake  they  may  reach  is 
not  known,  but  the  domes  and  islands  of  the  same  material  rising 
from  its  waters  have  their  bases  deeply  submerged. 

The  lithoid  and  thinolitic  varieties  are  thickest  at  the  lowest 
horizons  exposed.  The  dendritic  tufa  reaches  its  greatest  de- 
velopment near  its  upj^er  limit,  and  frequently  hangs  from  steep 
cliffs  like  a  massive  thatch.  In  some  instances  it  is  so  abun- 
dant at  elevations  of  from  200  to  300  feet  above  Pyramid  Lake, 
that  it  gives  a  decidedly  convex  outline  to  the  slopes  to  which 
it  is  attached. 

At  certain  localities  on  the  Carson  Desert  and  about  Pp'amid 
Lake  the  surface  of  the  lake  beds  partially  tilling  those  basins  is 
covered  over  large  areas  with  polygonal  blocks  having  rounded 
summits.  Each  block  in  these  closely  set  pavements  is  a  mnsh- 
room-shaped  growth  of  tufa  from  ten  to  twentj'  inches  or  more 
in  diameter.  These  blocks  were  at  first  circular  in  outline,  but 
pressed  against  one  another  as  they  enlarged,  and  thus  received 
an  angular  outline,  as  seen  from  above. 

The  base  of  each  separate  accumulation  of  tufa,  whether- a 
mushroom-shaped  growth  a  few  inches  in  diameter  or  a  great 
castle-like  form  a  hundred  feet  in  height  and  two  hundred  feet 
or  more  in  diameter,  is  a  pebble  or  nucleus  of  rock  about  which 
crystallization  began.  Wherever  there  was  a  solid  crag  in  the 
old  lake  suitable  for  the  attachment  of  the  lime  precipitated 
from  the  water,  it  became  incrusted,  and,  as  the  process  contin- 
ued, grew  into  an  imitative  form.  Detached  rocks  and  islands 
were  especially  favoraljle  as  centers  of  aecunmlation,  and  be- 
came hea%-ily  loaded.  The  borders  of  the  valleys,  where  com- 
posed of  solid  rock,  were  also  covered,  and  frequently  concealed 
Vieneath  p6ndant  masses  of  tufa  resembling  gigantic  honey- 
combs. 

Tlic  Mure  Solnhle  Salts. — As  shoAvn  by  the  average  composi- 
tion of  river  water,  about  one  half  of  the  total  solids  earned  in 
solution  by  surface  streams  is  calcium  carbonate.  This  is  the 
most  diflScult  of  solution  of  anv  of  the  salts  ordinarilv  found  in 


OTHER   CHEMICAL   DEPOSITS.  129 

such  waters,  and  the  first  to  be  precipitated  when  conceutratioii 
by  evaporation  takes  place.  The  more  soluble  salts  consist 
mainly  of  sodium  sulpliate,  sodium  carbonate  or  bicarbonate, 
sodium  chloride,  silica,  magnesium,  potash,  iron,  etc. 

The  amount  of  these  more  soluble  substances  carried  into 
Lake  Lahoutan  must  therefore  have  been  about  equal  to  the 
amount  of  calcareous  tufa  precipitated.  As  the  lake  never  over- 
flowed, these  salts  must  still  exist  in  its  now  nearly  desiccated 
basin;  yet,  in  riding  through  the  valleys  that  wei-e  formerly 
flooded,  no  deposits  of  the  salts  referred  to  can  he  foun<l,  at 
all  commensurate  with  the  vast  quantity  of  calcium  carbonate 
that  attracts  one's  attention.  The  disappearance  of  the  salts 
referred  to  seems  to  be  satisfactorily  explained  in  the  following 
hypothesis :  — 

After  the  last  gi'eat  rise  of  Lake  Lahontan,  there  was  a  long- 
continued  episode  during  which  its  basin  was  more  arid  than  at 
present.  Evaporation  during  that  time  is  thought  to  have  been 
equal  to  precipitation,  and  the  residual  lakes  were  reduced  to 
the  playa  condition ;  that  is,  the  remnants  of  the  gi-eat  lake 
gathered  in  the  lowest  depressions  of  its  basin  were  anmudl>- 
or  occasionally  evaporated  to  dryness,  and  their  contained  salts 
were  precipitated,  and  either  absorbed  by  the  clays,  etc.,  deposited 
at  the  same  time,  or  buried  beneath  such  mechanical  deposits. 
This  process  may  be  observed  in  action  in  many  of  the  valleys 
of  Nevada  in  which  ephemeral  lakes  occur.  The  broad,  naked 
playas  of  Black  Rock,  Smoke  Creek,  and  Carson  deserts,  as 
well  as  the  level  floors  of  the  basins  occupied  by  P>Tamid,  "Wiii- 
nemueca,  and  Walker  lakes,  are  in  support  of  this  livjiothesis. 
Should  the  lakes  just  mentioned  be  evaporated  to  dryness, 
playas  would  be  left  similar  to  those  in  neighboring  valleys  of 
less  depth.  It  is  beneath  tlie  level  floors  of  these  valleys  and 
lake  basins  that  the  more  soluble  salts  once  dissolved  in  the 
waters  of  Lake  Lahoutan  are  buried.  Borings  at  certain  locali- 
ties might  reveal  the  presence  of  strata  of  various  salts,  l)ut  in 
most  eases  they  are  probably  disseminated  through  givat  thick- 
nesses of  clay,  sand,  and  other  mechanical  sediments. 

Analyses  of  the  stratified  beds  laid  down  in  tho  basin  of  Lake 
Lahontan  show  that  they  are  charged  with  saline  matter  to  such 
an  extent,  that  the  total  (juantity  t>f  the  various  solnl)le  salts 
contained  in  them  is  certainly  equal  to,  and  probably  in  excess 
of,  the  calcareous  tufa  now  ^^sible  in  tlie  same  depressions. 


130  PRESENT   .VXD   EXTINCT   L.\KES   OF   NEVADA. 

The  Organic  Records. — The  evidence  derived  from  organic 
remains  indicates  that  Lake  Lahontau  throughout  its  higher 
stages  was  never  a  strong  saline  or  alkaline  solution.  Even 
during  the  abundant  precipitation  of  dendritic  tufa,  the  lake  was 
inhabited  by  moUusks  in  great  numbers,  and  was  probably  also 
the  home  of  fishes  of  large  size.  During  the  thinolitic  stage, 
when  its  waters  were  greatly  concentrated  by  evaporation,  the 
absence  of  fossils  indicates  that  it  was  uninhabited  by  either 
fishes  or  mollusks. 

SrMMARY  OF  THE  HiSTORY  OF  Laio^:  Lahontan. — The  combined 
results  of  a  somewhat  extended  study  of  the  physical,  chemical, 
organic,  and  other  records  left  by  Lake  Lahontan,  show  that  it 
furnishes  a  t^^iical  illustration  of  the  life  history  of  an  inclosed 
lake.  The  marked  difference  in  the  destiny  of  a  lake  that  never 
finds  an  outlet,  from  the  changes  experienced  by  a  normal  lake, 
may  be  strikingly  illustrated  by  contrasting  the  history  of  the 
Lahontan  l)asin  Avith  that  of  a  similar  basin  in  a  humid  region 
which  has  been  filled  to  overflowing,  and  been  drained  or  filled, 
and  transferred  into  a  teiTaced  valley. 

Lake  Lahontan  began  with  the  expansion  of  several  i>laya 
lakes  in  the  lowest  depressions  of  its  composite  basin.  These  rose, 
with  many  fluctuations,  until  they  became  imited,  and  continued 
to  increase  in  depth  and  extent  until  the  full  expansion  of  the 
first  maximum  Avas  reached.  This  growth  was  due  to  a  climatic 
change  which  caused  an  increase  in  precipitation  and  an  accom- 
panying decrease  in  evaporation.  Glaciers  existed  on  the  higher 
portion  of  the  Sierra  Nevada  and  on  some  of  the  basin  ranges 
to  the  east,  and  by  their  melting  assisted  in  the  flooding  of 
adjacent  valleys.  Then  came  a  time  of  aridity.  The  previously 
flooded  valleys  became  as  waterless  as  at  present,  and  possibly 
were  comiiletely  desiccated.  A  second  period  of  increased  humid- 
ity caused  the  basin  to  be  again  partially  filled.  The  waters  rose 
110  feet  above  the  level  of  Pyramid  Lake,  and  the  thinolitic  tufa 
was  precipitated  from  it.  The  character  of  this  deposit  indi- 
cates that  a  chemical  change  had  taken  place  in  the  lake  water. 
What  this  change  was  is  not  clearly  landerstood. 

After  the  crystallization  of  thinolite  had  gone  on  for  a  long 
period,  the  lake  rose  210  feet,  or  to  within  280  feet  of  its  first 
maximum;  and  the  heaviest  of  all  the  tufa  deposits,  the  den- 
dritic variety,  was  precipitated.  Aftei-  the  greater  part  of  this 
variety  of  tufa  had  been  formed,  the  lake  continued  to  rise,  and 


LIFE   HISTOKY   OF   LAKE   LAHONTAN.  I'M 

at  length  reached  au  horizon  30  feet  higher  than  at  the  time  of 
its  first  great  expansion.  At  the  highest  stage  the  water  lin- 
gered but  a  short  time,  and  no  chemical  precii)itates  remain  to 
record  it.  Two  terraces,  or,  in  other  localities,  two  emhaiik- 
meuts  of  gravel  resting  on  the  lithoid  terrace,  were  formed  dur- 
ing this  second  rise.  An  increase  in  depth  after  the  deposi- 
tion of  the  major  part  of  the  dendritic  tufa  is  showu  by  the 
presence  of  fine  mechanical  sediments  resting  on  it. 

The  recession  of  the  waters  after  the  second  rise  brought  all 
portions  of  the  basin  previously  sul)merged  within  the  reach  of 
waves  and  currents,  and  the  sheathings  of  tufa  were  in  part  cut 
away,  and  their  fragments  liuilt  into  embankments  and  terraces. 

The  waters  continued  to  fall,  with  many  fluctuations,  until 
the  basin  was  completely  dry.  All  of  the  salts  not  previously 
preciiaitated  were  dejiosited  as  desiccation  advanced,  and  became 
buried  or  absorbed  by  playa  clays. 

The  duration  of  the  post-Lahontan  period  of  desiccation  is 
unknown,  but  judging  from  the  length  of  time  that  would  1)6 
required  for  Pyramid,  Wiuuemucca,  and  Walker  lakes  to  ac- 
quire their  present  degree  of  salinity  under  existing  conditions, 
it  must  have  closed  about  three  hundred  years  since. 

Throughout  its  entire  history  the  lake  underwent  a  nuiltitude 
of  minor  oscillations.  These  are  imperfectly  recorded  by  a  large 
number  of  indefinite  terraces,  and  by  a  nuiltitude  of  narrow 
bands  of  varying  structure  in  the  tufa  deposit. 

The  main  featvu-es  in  the  fluctuations  of  Lake  Lahontan  coin- 
cide in  a  remai'kable  way  with  the  history  of  Lake  Bonneville, 
and  show  that  the  climatic  changes  to  which  they  were  due 
were  not  local.  It  is  assumed,  for  what  seem  valid  I'easons,  that 
the  two  high-water  stages  recorded  in  each  of  these  lakes  were 
synchronous  with  two  periods  of  ice  extension  over  nortlu'astern 
North  America  during  the  glacier  period.  If  this  correlatit)n 
proves  to  be  well  founded, — and  at  present  there  is  no  reason  to 
doubt  its  validity, — it  will  show  a  still  wider  extent  in  the  cli- 
matic changes  that  have  affected  the  lakes  of  Nevada. 

Intekpketation  of  the  Records  in  Tekms  of  Climate. — 
In  regions  where  the  mean  animal  rainfall  on  a  given  area 
exceeds  the  mean  anniial  evaporation,  it  js  manifest  that  an  in- 
closed lake  cannot  long  exist.  No  matter  how  deep  the  basin,  it 
nmst  ultimately  bo  filled  to  overflowing.  The  study  of  the  pres- 
ent geography  of  the  earth  shows,  that,  in  regions  where  the 


132  PRESENT  AND   EXTINCT   LAKES   OF   NEVADA. 

lueau  auuual  precipitatiou  exceeds  about  twenty  or  perhaps 
twenty-five  iuches,  iuelosed  lakes  do  uot  occur,  although  the 
topographic  conditions  may  be  favorable. 

These  and  other  considei-ations  lead  to  the  conclusion  that  the 
cliniatie  changes  which  led  to  the  flooding  of  the  Lahontan  basin, 
but  did  nut  permit  its  l)ecoming  tilled  to  overflowing,  were  not 
accompanied  by  heavy  rainfall ;  and  that  the  mean  annual  pre- 
cipitation throughout  its  history  was  less  than  twenty  or  twenty- 
five  inches. 

Remembering  that  the  principal  streams  flowing  to  Lake 
Lahontan  came  from  the  high  mountains  on  its  western  bor- 
der, and  that  at  the  time  of  its  greatest  expansion  its  water  sur- 
face was  less  than  one  quarter  of  its  catchment  area,  and  also 
that  evaporation  probably  decreased  as  the  rainfall  increased,  it 
seems  safe  to  assume  that  the  average  rainfall  over  Nevada  at 
the  time  it  was  transformed  into  a  lake  region  was  probably  not 
in  excess  of  ten  or  fifteen  inches  a  year. 

Considering  the  question  of  humidity  alone,  the  times  of 
marked  expansion  in  the  ancient  lakes  of  the  Great  Basin  indi- 
cate an  increase  in  mean  annual  precipitation,  and  times  of  con- 
tracted water  surface  a  decrease  in  rainfall.  Thus  interpreted, 
we  have  two  periods  of  increased  rainfall  and  of  relatively  great 
humidity,  separated  by  an  inter-lacustral  arid  period.  The  first 
period  of  precipitation  was  preceded  by  an  arid  period;  and  a 
similar  period  succeeded  the  last  rise,  and  continues  to  the  pres- 
ent day. 

The  sediments  of  lakes  more  ancient  than  those  just  described, 
and  containing  the  bones  of  many  extinct  animals  and  the  leaves 
of  a  luxuriant  flora,  also  occur  in  Nevada ;  but  of  this  older  chap- 
ter in  the  earth's  histoiy,  space  will  not  pei-niit  me  to  speak. 

BOOKS  OF   REFERENCE. 

Kixc,  Clarence.     Fnited  States  Geological  Exploiatiou  of  the  Fortieth  Parallel, 

vol.  i.  1878,  pp.  459-529. 
GiLBEKT,  G.  K.     Lake  Bonneville  (Monograph,  vol.  i.  1890,  U.  S.  Geological  Survey). 
Russell,  I.  C.     Lake  Laliontan  (Monograph,  vol.  xi.  1885,  U.  S.  Geological  Survey). 

Quaternary  Histoi-y  of  Mono  Valley,  California  (8fh  Annnal   Report,  U.  S. 

Geological  Survey,  1886-87,  pji.  261-394).   ' 

Geological   Reconnaissance  in   Southern  Oregon  (4th  .\nnnal   Report,  U.  S. 

Geological  Sun-ey.  18S2-83,  pp.  4.31-464). 

Geological   Reconnaissance   in   Central   Washington    (Bulletin  Xo.  108,  1893. 


U.  S.  Geological  Survey). 


PLATE  I 


I 


-LATE  II. 


.«^^V 


'fy^i 


s^b^K''"-'"^ 


<-. 


:.'^/^::i'fP"  ..■ ■■'/... 


'i^  Tohak  u  m  Ht 


Nac:,.  :      . 


"LATE  III. 


BEACHES  AND   TIDAL   MARSHES   OF   THE 
ATLANTIC   COAST. 


By  N.  S.  Shaler. 


Introduction. — The  essence  of  luodern  science,  the  quality 
which  the  beginner  in  its  study  needs  above  all  else  to  master, 
is  the  habit  of  patiently  seeking  to  disentangle  the  maze  of  na- 
ture, so  that  he  may  be  able  to  trace  the  orderly  associations  of 
events  in  what  seems,  to  the  ordinary  view  iit  least,  a  i)icture.sque 
jumble  of  unrelated  facts.  To  do  this  task  in  an  effective  way, 
the  student  should  take  up  some  class  of  actions  in  which  he  niaj^ 
trace  the  phenomena  from  one  step  of  their  growth  to  another, 
until  he  sees  how  they  fit  into  the  system  of  this  earth.  For  such 
a  task  there  is  perhaps  no  matter  which  better  lends  itself  to  his 
needs  than  that  of  beaches.  The  features  with  which  we  here 
have  to  deal  are  tolerably  well  exhibited  on  a  greater  or  less  scale 
in  all  parts  of  the  world  which  are  not  actual  deserts.  Thej^  are 
traceable  along  the  shores  of  tiny  pools  and  rivulets;  niajiy  of 
them  are  nearly  as  well  shown  in  the  snudler  as  in  the  larger 
examples;  and  certain  of  the  more  important  of  them  can  be 
more  easily  studied  in  the  instances  afforded  by  an  artificial 
pool  than  on  the  shores  of  the  ocean.  In  these  little  examples 
we  may  behold  in  a  very  limited  compass  many  of  the  i)rocesses 
by  which  the  land  was  formed  and  destroyed,  or 'rather,  we 
should  say,  made  over,  })y  the  ceaselessly  acting  agents  which 
change  the  shape  of  the  earth's  surface. 

To  obtain  the  first  preliminary  notion  of  what  a  beach  means, 
the  student  should  choose  some  place  on  the  margin  of  the  sea, 
or,  better,  on  the  shores  of  a  pond  or  rivei-,  where  soft  materials, 
such  as  beds  of  sand  and  gravel,  are  subjected  to  the  action  of 

(Copyright,  1895,  by  America'ii  Book  Company.) 
137 


138  BEACHES   .VXD   TIDAL   MAHSHES. 

the  waves.  Selecting  a  time  when  tlie  wind  is  blowing  toward 
the  shore,  he  may  note  that  the  waves  strike  the  bank  with  a 
certain  anioimt  of  force,  and  that  the  incoherent  rocky  matter 
crumbles  under  their  action.  Partly  by  the  stroke  of  the  waves, 
and  partly  by  the  dissohdng  effect  of  the  water,  the  earthy  ma- 
terial slips  down  the  cliff,  and  is  usually  distributed  over  a  gentle 
slope  extending  downward  and  outward  from  its  base.  In  this 
simple  group  of  facts  we  see  the  leading  princijiles  of  beach 
action,  which  is,  that  materials  which  are  brought  into  a  water 
basin  are  so  arranged  that  they  tend  to  form  a  sloping  mass  of 
debris,  the  higher  part  of  the  incline  being  next  the  cliff.  We 
may  indeed  define  a  beach  as  a  mass  of  detritus  which  has  been 
brought  into  its  jwsition  by  the  operation  of  waves,  more  or  less 
assisted  in  their  work  by  current  action.  As  we  shall  see,  how- 
ever, this  general  statement  has  to  be  extended  and  qualified,  in 
order  that  it  may  be  made  to  fit  the  numberless  special  groups 
of  l)eaches  which  the  varied  conditions  of  this  world  bring  about. 
The  student  of  beach  jihenomeua  may  well  1  tegin  his  observa- 
tions with  the  conditions  which  he  will  find  set  before  him  in 
the  little  rivulets  in  which  are  first  gathered  the  waters  of  a 
river  system.  This  field  of  action  is  particularly  well  fitted  to 
show  the  relation  of  beaches  to  the  other  work  which  is  done  by 
the  agency  of  water.  In  all  head-water  streams  it  is  easy  to  see 
how  rock  materials,  worn  away  from  their  bed  places  by  the 
action  of  frost  and  the  other  agents  of  decay,  are  brought,  at 
times  of  hea^■y  i"ain,  to  the  channels  of  the  streams,  and  thus 
placed  where  they  may  be  borne  gradually  downward  to  the 
ocean.  Watching  any  one  of  these  rivulets  when  it  is  swollen 
by  the  rainfall,  we  readily  note  that  in  the  middle  of  the 
channel,  where  the  water  is  deepest,  the  debris  moves  along 
with  much  gi'eater  rapidity  than  it  does  in  the  shallowei-  portions 
of  the  current  next  the  banks,  and  that  the  fragments  which  are 
traveling  in  this  central  part  of  the  streamlet  are  generally  much 
larger  than  those  which  are  in  the  part  of  the  jirocession  near  the 
shore.  ^Miere  the  brook  is  perhaps  ten  feet  wide  and  three  feet 
deep  in  the  middle,  shallo\ving  gradually  toward  the  banks,  the 
deeper  water  carries  onward  pebbles  several  inches  in  diameter, 
or,  if  the  bed  be  steej),  it  may  urge  forward  bowlders  a  foot  or  two 
in  cross  section ;  yet  toward  the  sides  of  the  torrent,  where  the 
depth  is  only  three  or  four  inches,  the  stream  is  seen  to  carry 
only  small  pebbles,  while  in   the   shallowest  fringe  of  water 


RIVER  BEACHES.  139 

nothing  but  the  flue  saud  is  in  motiou.  As  this  ditt'ereuce  iu 
the  energy  of  stream  action  is  not  only  curious,  but  of  gi-eat 
consequence  in  the  history  of  the  earth,  we  must  look  closely  to 
its  origin  and  effects. 

It  is  well  known  that  bodies  weigh  less  in  water  or  other 
fluids  than  in  the  air.  This  buoyancy,  as  it  is  called,  is  what 
causes  wood  or  even  porous  stone,  as  pumice,  to  float.  A  sim- 
ple experiment  of  this  principle  can  be  made  by  lifting  a  stone 
with  the  hand  out  of  a  basin  of  water.  As  long  as  it  is  sub- 
merged it  weighs  much  less  than  it  does  when  it  is  above  the 
level  of  the  fluid.  The  result  of  this  is  that  all  rock  material  is 
much  more  easily  truufUed  along  the  stream  beds  than  in  the 
open  air.  Next  we  have  to  note  the  fact  that  the  downward 
shoving  power  of  water  increases  at  a  singularly  rapid  rate  witli 
the  acceleration  of  its  speed.  Therefore  the  speed  with  wliicli 
water  moves,  profoundly  affects  the  value  of  the  work  wliidi  it 
can  perform. 

We  have  now  to  note  that  the  velocity  with  wliich  a  current 
or  stream  of  water  moves  depends  in  a  very  important  and  im- 
mediate way  on  its  depth,  which  depth  determines  the  retarding 
effects  of  the  friction  of  the  fluid  on  its  bottom.  Returning  to 
the  case  of  the  brook,  we  readily  perceive  that  the  stream  is 
flowing  several  times  as  fast  in  its  middle  part,  where  the  water 
is  deep,  as  next  the  shore,  where  it  is  shallow.  A  closer  study 
will  show  that  the  speed  of  motion  is  directly  proportional  to 
the  depth,  and  that  the  current  is  everywhere  swifter  on  or  near 
the  surface  than  it  is  next  the  bottom. 

River  Beaches. — We  are  now  in  a  position  to  see  liow  river 
beaches  are  formed  and  maintained  by  the  action  of  the  running 
water.  The  detritus  which,  especially  in  times  of  heavy  i-ain,  is 
swept  into  these  channels  from  the  steep  hillsides,  journeys  on 
as  best  it  may  in  the  varying  conditions  of  the  current.  The 
larger  stones  generally  keep  in  the  deeper  part  of  the  water, 
being  led  there  by  the  sloping  sides  of  the  channel.  Tlie  fine 
stuff"  is  often  whirled  by  the  eddies  into  the  shallow  parts  next 
the  banks,  into  poi-tions  of  the  bed  where,  because  of  the  friction 
which  the  current  encounters  in  moving  over  the  bottom,  the 
flow  is  less  speedy.  Attaining  a  depth  wliei-e  the  little  waves 
which  the  winds  create  can  affect  tliem,  the  particles  of  sand 
and  gi-avel  are  at  once  ai'ranged  in  the  form  of  a  beach ;  that  is, 
in  the  gently  curved  slope,  witli  its  higher  part  lying  against 


140  BEACHES  AXD  TIDAL  MARSHES. 

the  banks  which  confine  the  water.  In  the  production  of  this 
beach  the  principles  which  regulate  ciu-rent  movements,  and  the 
transportation  of  the  sediments  that  they  carry,  again  control 
the  action.  To  see  how  this  is  effected,  we  must  now  attend  to 
the  ciu'ious  movements  which  take  place  in  wave  motion.  Al- 
though it  is  easiest  to  study  the  features  of  waves  on  the  shore 
of  a  large  expanse  of  water,  a  great  lake  or  the  ocean,  all  that 
we  now  need  in  the  way  of  information  may  be  had  by  closely 
observing  the  wavelets  of  a  brook  or  small  river,  which  ai'e 
formed  when  a  strong  wind  is  lilowiug  across  the  water.  By 
noting  the  motion  f)f  any  floating  bits  of  wood,  we  pei'ceive  that 
the  wave  is  an  undulation  of  the  water  essentially  like  that  we 
see  in  a  sheet  of  cloth  when  it  is  shaken  by  the  hand  or  by  the 
wind ;  in  other  words,  the  wave  moves  on,  though  the  particles 
of  matter  tkrough  which  it  passes  do  not  go  forward.  When 
the  water  is,  say,  ten  times  as  deep  as  the  wave  is  high,  it  sweeps 
over  the  Ijottom  A\-ithout  much  effect ;  but  when  the  water  is  rela- 
tively shallow,  it  sets  the  finer  gi-ains  of  sand  in  motion  in  the 
direction  in  which  it  is  traveling,  each  wave  bobbing  them  along 
for  a  short  distance  as  it  passes  by.  As  the  undulation  comes 
into  shoaler  water,  it  rubs  upon  the  bottom  with  energy,  which 
increases  with  the  shoaling ;  so  that  next  the  shore  it  commonly 
has  sufficient  power  to  drag  a  good  deal  of  sand  with  it.  In 
this  manner  the  greater  part  of  the  sand  of  river  beaches  is 
taken  from  the  deeper  parts  of  the  stream  and  carried  against 
the  shore. 

Some  parts  of  the  sand  of  river  beaches  are  swung  out  of 
the  channel  by  eddies.  Those  whirling  motions  of  the  waters 
tend  to  throw  sand  or  even  light  pebbles  to  then*  borders,  and 
so  bring  detritus  against  the  bank  or  into  shallow  water,  where 
the  waves  may  be  able  to  move  it.  Again,  in  the  banks  of  the 
lai'ger  streams  there  is  commoidy  a  mass  of  alluviinu  or  debris 
which  the  river  has  at  former  times  brought  down  and  built 
into  a  plain,  through  which  the  stream  now  wandei's.  We  may 
readily  see  that  this  ])lain  is  generally  forming  on  one  side,  and 
cutting  away  on  the  other.  As  the  bank  is  undermined  on  the 
wasting  side,  the  sand  and  gravel  which  are  given  to  the  stream 
are  generally  built  for  a  time  into  a  beach  a  little  way  below  the 
point  where  they  are  committed  to  the  current. 

It  is  characteristic  of  the  sand  in  river  beaches,  as  we  shall 
find  it  to  be  also  of  that  in  sea  beaches  in  general,  that  it  is 


SEA   AND   LAKE   BEACHES.  1-H 

usually  in  tolerably  constant  motion,  the  particles  .iourneying 
slowly  downstream.  Each  time  the  waves  stir  the  gi'ains  of  sand, 
the  latter  move  a  little  distance  on  their  way  to  the  sea.  At 
everj^  season  of  floods,  the  deposit,  being  covered  by  deep  and 
swift-moving  water,  is  destroyed  or  gi-eatly  diminished  in  mass, 
to  be  again  developed  when  for  a  cousideraljle  period  the  water 
re)nains  at  neai-ly  one  level.  In  fact,  all  the  debris  in  a  brook  or 
river  is  normally  in  a  condition  of  downward  movement,  which 
is  only  for  a  time  interrupted  by  low  water,  when  for  a  season 
the  stream  takes  on  a  character  of  separate  pool-like  areas  of 
water  separated  from  each  other  by  rapids.  It  is  dm'ing  these 
periods  of  relative  stagnation  of  the  current,  when  each  pool  is 
much  like  a  small  sea,  that  distinct  beaches  are  formed.  Their 
presence,  indeed,  may  be  taken  as  an  indication  that  the  river  is 
at  its  low  stage  of  flow.  Imperfect  and  temjiorary  as  are  the 
beaches  beside  the  streams,  they  serve  to  show  the  usual  condi- 
tions of  contact  of  land  and  water,  so  that  the  student  who  is 
denied  access  to  the  nobler  instances  of  such  structures  on 
the  margins  of  the  seas  or  lakes  may  well  use  them  for  his 
inquiries. 

Sea  AND  Lake  Beaches.  —  Turning  from  the  rivers,  where  the 
beaches  are  only  incidental  phenomena  in  the  work  of  water,  we 
shall  now  consider  the  shore  work  in  the  seas  and  lakes,  where 
those  features  are  almost  everywhere  to  be  noted.  In  these 
basins,  where  the  water,  except  for  the  swing  of  the  tides,  com- 
monly remains  without  appreciable  change  of  level  for  centm-ies 
or  for  thousands  of  years,  thei'e  has  usually  been  time  for  debris 
to  gather  along  the  shores  in  such  (juantities  that  it  attords  the 
foundation  for  a  beach.  Here  and  there  along  the  coast  we  find 
where  the  land,  having  been  cai'ved  into  steeps  by  the  action  of 
streams  or  glaciers,  has  then  by  a  downsinking  process  ])ecn 
brought  below  the  sea  level  at  so  recent  a.  period  that  the  de- 
struction of  the  cliffs  aided  ])y  the  action  of  the  waves  has  not 
yet  sufficed  to  fill  the  sea  at  .their  base  so  as  to  form  a  beach. 
Again  it  happens,  jiarticularly  about  the  North  Atlantic,  that  the 
glaciers  of  the  last  ice  time  swept  far  out  to  sea  beyond  the 
shore  line,  destroying  the  ancient  beaches;  so  that  when  the 
frozen  waters  melted,  the  sea  level  came  again  against  steeps, 
forming  deep  water  at  their  base.  That  this  is  an  exceptional, 
indeed  we  may  say  a  temporary,  condition  of  the  contact  of  sea 
and  land, — one  which  is  everywhere  in  process  of  being  over- 


142  BEACHES  AND  TIDAL  MAKSHES. 

come, — can  i-eadily  be  seen  by  any  one  who  will  watch  such  a 
shore  during  a  time  of  heavy'  storm. 

Approaching  in  a  time  of  storm  a  rock-bound  coast,  where 
the  cliffs  descend  into  deep  water,  the  observer  may,  from  some 
projecting  headland,  look  along  the  shore  so  as  to  behold  the 
majestic  spectacle  which  the  surges  afford  as  they  nish  against 
the  shore.  Four  or  live  times  a  minute  the  waves,  having  a 
height  of  maybe  twenty  or  thirty  feet,  charge  against  the  ram- 
part, and  break  into  spray  and  foam  as  they  meet  the  steep. 
Where  the  rock  is  tirm-set  and  smooth,  the  blows  have  no  dis- 
tinct ett"ect;  but  wherever  there  is  a  weak  place  in  the  defenses, 
the  waves  have  hollowed  out  a  recess,  which  may  be  a  consider- 
able cave,  into  which  the  swift-moving  water  i-ushes  with  a  fury 
which  is  intensified  by  the  narrowing  space  of  the  channel.  In 
such  a  recess  the  waves  generally  find  some  bits  of  stone,  which 
they  swing  against  the  walls,  thus  deepening  and  widening  the 
recess.  In  time  the  overhanging  rock  falls  down,  thus  serving 
to  shallow  the  water  at  the  base  of  the  cliffs.  This  quarrying 
work  is  aided  by  the  action  of  frost  and  other  agents  of  decay, 
which  are  constantly  at  work  on  the  face  and  summit  of  the 
precipices.  Each  year  a  quantity  of  debris  is  added  to  the  heap 
which  lies  imder  the  water.  In  this  accumulation  of  rocky  mat- 
ter there  enters  a  large  amount  of  organic  waste,  the  hard  ]>arts 
left  at  the  death  of  various  shell-bearing  animals,  such  as  abound 
on  the  bottom  of  the  sea  near  the  land.  In  this  way  a  steeply 
sloping  mass  is  built  up,  which  in  time  has  its  upper  part  so  near 
the  surface  of  the  water  that  the  fragments  of  which  it  is  com- 
posed may  be  moved  by  the  waves. 

When  the  submarine  talus  at  the  foot  of  an  ocean  cliff  has 
attained  an  elevation  which  permits  the  waves  effectively  to  act 
upon  it,  a  true  beach  is  speedily  formed.  As  soon  as  the  masses 
of  stone  are  in  a  position  to  be  tossed  about  by  the  surges,  thej^ 
are  thrown  in  times  of  storm  against  the  base  of  the  cliff.  We 
may  often  hear  the  sound  of  the  blows  thej-  deliver,  adding  a 
harsh,  crashing  note  to  the  roar  of  the  breakers.  The  effect 
of  this  work  is  soon  marked  in  tlie  I'ounded  form  of  the  stones 
and  in  the  excavation  whicli  has  l)een  made  as  a  continuous 
indentation  at  the  foot  of  the  cliffs  which  thus  are  nuuU'  to 
ovei'hang.  In  this  condition  the  destruction  of  the  hardest  and 
firmest  kind  of  rocks  goes  on  at  a  rapid  rate,  for  gi-a\ity  now 
aids  the  other  powers  of  waste  in  a  most  eft'octi\-o  mannor.    From 


EOLLING   BEACHES.  143 

time  to  time  masses  from  the  jutting  face  fall  to  the  level  of  the 
sea.  Geuerally,  in  falling,  they  bi-eak  into  bits  small  enough  to 
be  tossed  about  by  the  greater  waves,  and  so  in  time  serve  as 
battering  instruments  for  the  further  assault  of  the  land.  The 
complexity  of  this  erosive  work  is  gi-eat  (a  volume  could  be  writ- 
ten about  it);  but  enough  has  1)een  said  to  show  how  effectively 
the  land  may  be  worn  when  there  is  a  chance  for  the  waves  to 
hurl  stones  against  its  steep  seaward  faces. 

Rolling  Beaches. — As  the  further  construction  of  the  young 
beach  proceeds,  the  mass  of  debris  widens,  and  its  slope  to  the 
seaward  becomes  more  gentle,  until  it  finally  forms  a  rather 
wide  strand  having  a  slope  of  not  more  than  ten  degrees'  decliv- 
ity. Wliere  the  sea  floor  was  originally  level  up  to  tlie  liase  of 
the  crags,  there  is  now  a  talus  slojjing  from  the  level  of  the  high 
tide  to  the  distance  of,  it  may  be,  half  a  mile  outward.  As  this 
talus  gains  in  wndth,  it  serves  to  protect  the  cliffs  against  the 
blows  of  the  waves.  Only  those  of  gi-eater  storms  now  attack 
the  fii'm  rock;  the  surges  of  ordinary  times  spend  their  forces  on 
the  bowldery  and  pebbly  matter.  At  this  stage  the  accumula- 
tion of  detritus,  or  at  least  the  ui>per  part  of  it,  becomes  a  rdl- 
ing  hcac]i, —  a  curious  and  most  important  mill,  in  which  stone 
is  ground  to  the  state  of  sand  and  mud. 

If  the  student  desires  to  see  the  rolling  beaches  in  operation, 
he  must  visit  the  shore  when  there  is  a  strong  wind  l)lowing 
upon  the  coast.  An  inspection  made  in  good  weather  will  not 
give  the  desired  lesson,  for  the  light  waves  of  such  a  time  do  not 
suffice  to  set  the  mill  in  motion.  When  the  seas  break  with 
their  fi'dnts  ten  feet  oi-  imn-o  in  height,  they  strike  a.  ]>lo\v  strong 
enough  to  send  to  and  fro  rounded  fragments  of  rock  which 
are  three  or  four  feet  in  diameter.  With  the  advance  of  the 
waves  these  bowlders  are  driven  up  the  beach.  If  the  seas  are 
powerful  enough,  the  pebbles  may  be  dashed  against  the  cliff 
whence  they  came ;  more  often  they  roll  up  and  down  until  they 
are  worn  out.  In  times  of  stonn  the  stones  of  a  rolling  lieach, 
sometimes  to  the  depth  of  two  or  three  feet,  are  carried  to  and 
fro  with  the  advance  and  retreat  of  the  waves.  In  tliis  move- 
ment the  bits  roll  over  one  anothtM-  inuch  in  the  maimer  of  mill- 
stones. The  softer  are  rajiidly  ground  to  the  state  of  sand  or 
mild,  in  which  state  the  waste  is  readily  cai-ried  away  by  the 
currents  to  the  open  sea. 

Although  a  large  part  of  the  pebbles  which  are  found  on 


144  BEACHES  AND  TIDAL  MARSHES. 

any  bowlder  beach  have  made  their  way  along  the  shore  from 
promontories  where  the  fragments  are  broken  off  bj^  the  waves, 
another  and  perhaps  more  considerable  part  of  these  stones  is 
brought  in  from  the  sea  bottom  by  the  action  of  various  marine 
plants.  Wherever  the  sea  floor  next  the  shore  and  in  shallow 
water  is  strewn  with  pebbles  derived  from  ancient  glaciers,  or 
perhaps  formed  on  beaches  which  now  lie  below  the  smface  of 
the  water,  seaweed  becomes  attached  to  these  fragments  of  rock, 
finding  their  surfaces  convenient  places  on  which  to  fix  its 
rootlike  attachments.  Almost  all  these  species  are  provided 
with  air  vesicles,  which  serve  to  keep  their  stems  and  branches 
upi'ight :  therefore  when  they  become  large,  they  exercise  a  cer- 
tain inilliug  action  on  the  stones ;  and  the  waves,  as  they  pass 
by,  pull  upon  the  smfaces  of  the  plant.  The  result  is  that  in 
time  of  storm  the  stone  is  lifted  above  the  bottom  and  borne 
toward  the  beach.  A  few  strokes  of  the  waves  serve  to  detach  the 
plant,  after  which  the  pebble  becomes  a  part  of  the  rolling  beach, 
whereon  it  is  in  time  gi'ound  to  powder. 

Many  of  the  pebbly  beaches  in  New  England  are  entirely  sup- 
plied by  the  action  of  seaweeds ;  and  one  small  island  near  the 
coast  of  Cape  Ann,  which  is  no  more  than  a  rolling  beach  washed 
by  the  waves,  appears  to  be  maintained  by  the  constant  importa- 
tion of  pebbles  which  are  plucked  from  the  bottom  in  the  man- 
ner above  described.  The  same  process,  with  shells  taking  the 
place  of  pebbles,  may  be  traced  along  the  sandy  shores  of  all  the 
continents.  In  fact,  the  gi-eater  part  of  the  shells  found  on  some 
of  the  Atlantic  sand  beaches  which  have  been  studied  by  the 
writer  owe  their  transportation  from  the  bottom  to  the  strand 
to  the  action  of  seaweeds,  or,  in  some  cases,  to  the  similar  effect 
exercised  by  the  growth  of  plant-like  animals,  such  as  sertiilarians, 
which  have  become  attached  to  the  hard  parts  of  the  mollusks. 

Action  of  Wa\ts  and  Tides  in  the  Foemation  of  Beaches. — 
The  energy  of  the  sun  sets  the  air  in  motion,  and  the  wind 
causes  the  waves,  so  that  it  is  solar  force  which  is  imparted  to 
the  waves.  Moving  over  the  deejier  parts  of  the  sea,  these  undu- 
lations have  probably  no  effect  on  the  bottom.  As  the  wave 
comes  nearer  the  shore,  and  enters  the  shallowest  parts  of  the  sea, 
it  begins  to  drag  on  the  bottom.  This  action  is  not  considerable 
until  the  depth  is  less  than  two  hundred  feet,  where  the  ordinarily 
great  wave  is  com]»etpnt  to  move  sand  up  the  slope  toward  the 
shore.    As  the  water  still  further  shaUows,  the  scraping  movement 


ACTION   OF   WAVES   AND   TIDES.  145 

increases,  until  it  can  move  at  fii'st  the  smaller  pebbles,  and  at  last 
the  bowlders  of  great  weight.  The  result  of  this  action  is  that 
the  waves  which  roll  on  a  shore  are  effective  in  moving  frag- 
ments from  a  considerable  depth  to  the  strand.  If  this  were  the 
only  source  of  motion  along  the  coast,  the  effect  would  be  to 
heap  up  a  great  mass  of  debris  at  about  the  level  of  high  tide. 
There  are,  however,  as  we  shall  now  see,  many  other  influences 
at  work  which  have  a  large  share  in  determining  the  form  of  a 
beach. 

Moving  over  the  deep  sea,  a  wave  proceeds  as  an  oscillation 
or  wrinkle  of  the  water,  which  is  substantially,  as  before  noted, 
like  the  undulations  of  a  shaken  cloth.  Oidyin  a  verj'  small 
measure  does  the  water  go  forward  in  the  direction  iu  which 
the  wave  is  moving.  When,,  however,  the  surge  comes  into 
shallow  water,  its  form  and  the  character  of  its  motion  undei'go 
important  changes,  which  progress  with  the  shoaling.  The  wave 
shortens  up,  becoming  relatively  higher  and  steepei' ;  it  also  i)n- 
parts  a  stronger  forward  movement  to  the  water.  The  shorten- 
ing and  steepening  of  the  wave  is  brought  about  in  the  following 
manner :  Coming  ever  into  shallower  water  as  it  nears  the  shore, 
the  surge  finds  the  friction  due  to  the  bottom  greatest  iu  its  front 
part :  this  part  is  therefore  proportionately  more  retarded  than 
the  following  portion  of  the  swell,  Avhich  thus  tends  to  overtake 
the  front.  As  water  is  practically  imcompressible,  the  wave  has 
to  increase  in  height.  This  principle,  which  is  called  the  conser- 
vation of  areas,  can  well  be  illustrated  by  flexing  a  piece  of  paper, 
pushing  the  arch  over  a  table,  and  shortening  the  base  as  it  nears 
an  imaginary  shore  line. 

An  interesting  cooperative  work  in  the  action  of  waves  iind 
tides  is  effected  throiigli  a  peculiar  movement  of  the  sea  known 
as  the  undertow.  AVlien  the  waves  roll  heavily  in  upon  a  shelving 
coast,  a  considerable  amount  of  water  contained  in  the  upper  part 
of  the  surges  moves  in  upon  the  shore  more  rapidly  than  that 
m  the  under  part  of  the  wave.  This  incoming  water,  having  to 
escape  eventually  seaward,  finds  its  way  out  along  the  bottom. 
Those  who  are  accustomed  to  swim  along  the  coast  where  the 
bottom  is  shallow,  and  at  times  wIkmi  the  surf  is  heavy,  have 
often  found  themselves  drawn  away  from  the  land  by  this  un- 
dercurrent. It  may  well  be  noted  that  the  stream  never  affects 
the  upper  two  feet  or  so  of  the  sea,  and  rarely  has  strength  save 
below  the  level  of  three  feet.     Thus  a  swimmer  wlio  takes  pains 


146  BEACHES   AND   TIDAL   MAKSHES. 

iu  his  movements  that  no  part  of  his  body  is  deeply  immersed 
can  readily  make  his  way  baok  to  the  land. 

The  eli'eet  of  the  imdertow,  which  is  strongest  when  the  waves 
are  attacking  the  shore  -svith  the  greatest  energy,  is  to  draw  the 
line  sediments  away  from  the  immediate  coast  line,  brin<ring  the 
detritus  far  enough  out  to  sea  for  it  to  be  taken  by  the  tidal  cur- 
rents, which  convey  it,  it  may  be,  for  many  miles  away  from  the 
coast  line. 

If  a  wave  suffered  no  other  change  as  it  approached  a  shore 
save  that  due  to  the  shortening  of  its  width,  the  result  would  be 
the  formation  of  surges  of  vast  height,  which  would  strike  upon 
the  coast  line  with  many  times  the  energy  which  they  actually 
possess.  The  fact  is,  that  as  soon  as  the  wave  arrives  in  water 
sufficiently  shallow  to  hinder  its  forward  motion,  and  thus  to 
bring  about  the  increase  in  height,  the  friction  which  it  encoun- 
ters progressively  tends  to  exhaust  the  euergj-  which  is  stored  iu 
the  undulation.  In  the  existing  conditions  of  our  coast  lines, 
probably  the  greater  pait  of  the  enei-gy  of  the  waves  is  applied 
to  the  bottom  of  the  shallows  which  they  traverse  before  they 
attain  the  beaches  or  cliffs.  In  these  shallows  they  impel  the 
detritus  up  the  slope,  and  cast  it  upon  the  shore.  If  this  action 
were  not  opposed  by  the  work  of  the  tides,  the  effect  would  be 
to  gi-eatly  increase  the  amount  of  sand  and  fine  i)ebbles  which 
we  find  at  the  contact  of  sea  and  laud;  but  the  work  of  the  tidal 
oscillation  is  distinctly  to  hinder  and  limit  the  invasion  of  sand 
from  the  continental  shelf. 

As  the  tidal  wave  rushes  in  ui;>on  a  coast,  it  has,  when  it 
comes  from  the  deejier  sea,  a  rate  of  advance  of  several  hundred 
miles  per  hour;  but,  owing  to  the  slight  amount  of  elevation 
which  it  gives  to  the  waters,  it  exercises  at  first  only  a  small 
dragging  power  on  the  detritus  of  the  ocean  floor.  The  nearer 
it  comes  to  the  shore,  the  gi'eater  this  dragging  action,  because 
of  the  shallowing  of  the  water;  but  the  effect  is  rarely  gi-eat 
enoiigh  to  move  more  than  coarse  sand  or  small  pebbles.  As 
the  tide  comes  toward  the  land,  these  movable  fragments  are 
carried  up  the  slope  which  leads  to  the  shore.  As  the  tidal  wave 
goes  out,  the  bits  journey  away  from  the  coast.  It  is  easy  to 
see  that,  as  the  movement  takes  place  up  and  down  the  sloping 
floor  of  the  sea,  the  effect  will  be  to  cany  the  sand  and  pebbles 
farther  and  farther  from  the  shore,  and  this  for  the  reason  that 
they  will  move  farther  with  a  given  tidal  impulse  in  the  direc- 


ACTION   OF   THE   A\TND.  147 

tion  in  which  the  bottom  inclines.  In  this  way  the  tides,  by 
dragging  materials  from  the  beaches  and  shallows  toward  the 
deep  sea,  serve  ever  to  extend  the  continental  shelf. 

The  action  of  waves  and  tides  on  the  sands  of  the  shallow 
waters,  though  in  general  of  a  contrasted  nature,  is  not  uniformly 
so.  The  surges  act  only  in  times  when  gales  blow  upon  the 
coast;  while  the  swingings  of  the  water  which  are  due  to  the 
attraction  of  sun  and  moon  operate  with  something  like  uni- 
formity, varying  only  as  these  planetary  bodies  unite  or  oppose 
their  influences  at  the  periods  of  spring  or  neap  tides.  The 
general  effect  of  these  combined  actions  is  to  mak(^  tlie  amount 
of  sand  which  is  gathered  on  any  beach  from  time  to  time  quite 
variable. 

Action  of  the  AVind  in  the  Formation  of  Beaches. — There 
is  yet  another  cause  of  much  diversity  in  the  amount  of  sand 
which  we  may  find  upon  a  beach.  This  is  due  to  the  action  of 
the  wind.  So  long  as  the  debris  along  the  coast  is  covered  with 
water,  the  wind  can  act  upon  it  only  by  means  of  the  waves  or 
currents  whicli  it  induces  in  the  fluid ;  when,  however,  the  sand 
is  bared  by  the  retreating  tide,  it  (juickly  di'ies,  and  in  this  state 
is  easily  moved  about  by  the  air  streams  when  they  have  a  con- 
siderable speed.  Blowing  upon  the  shore,  the  winds  carry  the 
sand,  and  even  small  pebbles,  from  the  stretch  of  surface  between 
high  and  low  tides  above  and  ])eyond  the  verge  of  the  waters, 
usually  accumulating  the  material  in  the  heaps  known  as  dioics. 
When  the  wind  blows  offshore,  as  it  prevailingly  does  aloug  the 
Atlantic  coast  of  North  America,  it  carries  the  dry  sand  back 
into  the  sea,  where,  if  the  conditions  favor,  it  may  be  removed 
by  the  tidal  and  other  currents  to  a  distance  from  the  land.  In 
tills  way  tlie  accumulations  of  sand  on  beaches  along  the  east- 
ern coast  of  the  United  States  are  much  restricted.  Where  the 
])revailing  winds  come  in  upon  shores  which  are  bordered  by 
sand  beaches,  sand  dunes  always  abound.  These  accumulations 
are  indeed  accunite  gnnges  wf  the  averag(^  direction  of  the  winds 
which  are  strong  enough  to  move  sand.  In  their  slighter  forms 
sand  dunes  are  inconspicuous,  but  where  they  are  well  devel- 
oi)ed  they  afford  some  of  the  most  striking  features  which  are 
found  at  the  contact  line  of  sea  and  land.  They  are,  moreover, 
in  certain  cases,  of  no  small  importance  in  the  history  of  the 
shore  lands.  We  shall  thei-efore  note  some  of  their  more  im- 
portant features. 


148  BEACHES   AND   TIDAL   XIAKSHES. 

Sand  Dunes. — ^'hen  the  sand  is  driven  up  the  slope  of  a 
beach  to  a  point  beyond  the  high-water  level,  it  at  once  escapes 
from  the  field  in  which  it  was  subjected  to  the  forming  and  uni- 
forming actions  which  make  the  grains  and  dispose  them  on  tlie 
smooth  incline  of  the  shore.  When  the  wind-blown  fragments 
come  to  the  top  of  the  beach,  they  encounter  a  relatively  rough 
suiface  on  whicli  there  are  usually  abundant  tussocks  of  rough 
gi-ass  or  of  other  plants ;  these  diminish  the  energj'  of  the  wind, 
which  on  the  more  open  shore  had  full  sweep,  and  so  serve  to 
bring  the  grains  of  sand  to  rest.  As  soon  as  a  little  heap  is 
thus  formed,  it  affords  a  yet  better  shelter  on  its  landward  side, 
and  so  gives  the  essential  conditions  for  the  gi-owth  of  a  dune. 
Thenceforth  the  jjrocess  is  very  simple :  the  flying  bits  move  up 
the  seaward  face  of  the  mound,  slip  over  its  summit,  and  come 
to  rest  on  the  leeward  face  of  the  elevation.  As  the  sand,  even 
when  it  appears  very  barren,  contains  much  food  for  plants, 
many  species  have  become  specially  modified  to  suppoi't  life  in 
the  difficult  conditions  which  the  dunes  afford.  The  most  of 
these  plants  belong  in  the  groups  of  gi'asses,  of  which  the  well- 
known  hench  f/rass  is  the  most  widely  distributed  and  best- 
known  form.  This  interesting  species  has  very  long  and  strong- 
grooving  roots,  which  enable  it  to  seek  a  supply  of  water,  as  the 
plants  have  to  do,  at  a  gi'eat  depth  beloAv  the  surface.  Its  leaves 
are  remarkably  tough,  and  are  thus  fitted  to  withstand  the  rude 
ti-eatment  of  the  storm  winds.  This  plant,  hke  others  of  its 
kindred,  but  in  a  yet  more  efficient  way,  increases  not  only  by 
its  seed,  but  by  means  of  runners  or  horizontally  extended  roots, 
which  grow  with  such  rapidity  that  they  may  extend  for  the 
distance  of  ten  feet  or  moi*e  in  a  year.  From  point  to  point 
these  runners  give  off  vertical  shoots,  which  estal)lish  the  crown 
of  a  new  plant ;  these  horizontally  disposed  roots  also  put  forth 
a  great  number  of  fibrils,  which  enmesh  the  sand  so  as  to  make 
it  difficult  for  the  strongest  blast  to  disturb  the  mass. 

On  account  of  the  vegetation  which  occupies  the  top  of  a 
dune,  a  considerable  store  of  the  sand  which  is  driveu  upon  the 
hiU  is  held  upon  the  summit :  the  elevation  thus  gi-ows  in  height. 
This  gi'owth  may  go  on  until  the  mass  rises  a  hundred  feet  or 
more  above  the  level  of  its  base,  while  its  width  and  length  may 
be  several  times  as  great.  As  the  conditions  which  determine 
the  formation  of  these  curious  products  of  the  l)eaches  are  pecul- 
iar and  irregular,  the  slopes  and  arrangements  of  dune  hUls  at 


m^ 


SAND   DUNES.  149 

first  sight  appear  to  be  more  disorderly  than  is  the  case  with  any 
other  gi'oups  of  shore  features.  This  apparently  confused  natui-e 
of  dunes  is  in  great  part  due  to  the  fact  that  they  alone,  of  all 
the  elevations  of  the  laud,  have  the  singular  habit  of  marching 
away  from  their  point  of  origin,  it  may  be  for  gi-eat  distances 
across  the  country. 

On  the  seaward  side  of  the  dune,  because  of  the  euergA-  of 
the  wind,  at  times  when  storms  blow  ripon  the  coast,  the  blast 
digs  the  dry  sand  from  among  the  roots  of  the  vegetation,  and 
sends  the  uprooted  plants  and  sand  together  over  the  top  of  the 
hill  to  its  landward  side.  So  rapidly  does  this  jn-oct'ss  go  on, 
that  in  a  single  jirotracted  gale  a  dune  thirty  feet  high  may 
be  moved  back  from  the  shore  for  a  distance  of  fifty  feet  or 
more.  As  the  marching  mass  of  sand  journeys  away  from  the 
coast,  various  causes  serve  to  resti-ain  its  movement.  It  is  e\-er 
coming  into  districts  where  the  air  moves  less  swiftly.  As  the 
grains  of  sand  decay,  they  begin  to  cement  togethei-, — a  process 
which  dkectlj'  hinders  the  work  of  the  wind  and  favors  the 
growth  of  plants:  hence  it  comes  about  that  the  advance  of 
a  dune  is  gradually  slowed,  and  in  the  end  the  dune  comes  to 
rest.  Yet  in  some  eases  they  have  been  observed  to  journey  for 
as  much  as  ten  miles  from  the  beaches  next  which  they  were 
formed.  In  some  instances  they  have  overwhelmed  villages  and 
desolated  extensive  tracts  of  fertile  land. 

It  not  infrequently  happens  that  dunes  of  considerable  size 
form  on  the  shores  of  fresh-water  lakes.  Thus  some  of  the  most 
important  of  these  wind-])lown  hills  in  this  country  lie  at  the 
southern  end  of  Lake  Michigan.  In  such  cases  we  always  find 
that  the  sand  is  derived  from  the  moving  of  beds  of  a  sandy 
natui-e,  which  are  broken  up  by  the  waves.  In  yet  other  and  rarer 
instances,  dunes  foi-m  along  the  1)anks  of  rivers  whei-e  th(>  alluvial 
cliffs  are  sufficiently  sandy  to  afford  a  considerable  supply  of  fine 
detritus  to  the  winds.  As  these  fluviatile  dunes  cannot  ordina- 
rily go  far  before  they  enter  fields  thickly  covered  with  vegeta- 
tion, they  rarely  wander  more  than  a  fi!W  hundred  feet  before 
they  become  densely  covered  with  plants,  and  so  are  bound 
down.  Moreover-,  in  the  constant  swingings  of  river  channels 
through  their  alluvial  plains, — a  movement  which  brings  about 
a  washing-over  of  all  the  deposits  of  those  terraces  in  a  brief 
geological  time, — such  dunes  are  apt  to  be  destroyed  before 
they  attain  any  great  size. 


150  BEACHES  AND  TIDAL  MAKSHES. 

S.^JO)  Beaches. — We  must  uow  tuvn  again  to  the  develop- 
ment of  sand  beaches,  and  theu"  rehition  to  the  physiography  of 
any  shore.  The  first  jjoint  to  be  noted  is  that  the  beaches  com- 
posed of  sand  are  vastly  more  extensive  than  are  those  which 
are  occupied  by  bowlders.  On  the  Atlantic  coast  of  the 
United  States,  which  affords  a  fair  gauge  for  a  determina- 
tion as  to  the  proportion  of  shore  lines  in  general,  the  sand 
beaches  probably  oceujiy  at  least  ten  times  as  much  of  the 
sea  front  as  those  which  are  composed  of  pebbles.  In  pai-t 
this  excess  of  sand  on  the  shores  is  to  be  attributed  to  the 
fact  that  the  rivers  bring  forth  a  certain  amount  of  material; 
moreover,  a  considerable  part  of  the  fine-ground  detritus  which 
occuiiies  the  northern  i)art  of  the  continent  owes  its  comminu- 
tion to  the  action  of  the  glaciers  which  recently  covered  that 
land.  The  share  of  the  marine  agents  in  these  materials  has 
been  limited  to  their  transportation  and  arrangement.  It  is, 
however,  evident  that  there  are  other  important  conditions 
which  have  affected  the  history  of  sand  grains,  and  exerted 
a  very  great  influence  in  promoting  their  resistance  to  the 
influences  which  lead  to  their  decay,  and  thereby  led  to  the 
accumulation  of  arenaceous  matter  along  the  sea  border.  These 
conditions  must  now  be  considered. 

It  should  in  the  first  place  be  noted,  that  ordinary  sand  con- 
sists normally  of  quartz  crystals  which  have  been  split  along 
their  cleavage  planes  to  the  jioint  where  the  fragments  are  no 
longer  easily  broken;  next,  that  this  substance  is,  of  all  the 
connnon  minerals  of  our  rocks,  the  one  which  is  least  readily 
affected  by  the  agents  of  decay;  moreover,  it  has  a  relatively 
low  specific  gl•a^dty,  and  is  also  very  hard,  so  that  when  tossed 
al>out  by  the  waves  it  does  not  strike  with  violence,  and  so  is 
much  less  subjected  to  wearing  than  most  other  rocks.  In  ad- 
dition to  these  protective  features,  and  much  more  important 
than  they,  is  another  and  peculiar  qualitj^  which  sand  acquires 
when  it  is  com}>letely  wetted.  In  this  state  the  gTains  lying 
with  their  faces  against  one  another  hold  the  water  between  them 
in  a  manner  which  makes  it  nearly  impossible  to  force  the  neigh- 
boring surfaces  together.  This  can  be  readily  seen  l)y  apj>lying 
pressure  to  wetted  sand.  Such  force  serves  to  squeeze  out  a 
portion  of  the  water ;  but,  even  when  applied  at  the  rate  of  a 
thousand  pounds  to  the  square  foot,  there  remains  enough  of 
tiie  fluid  between  the  grains  of  sand  to  keep  them  somewhat 


BAKKIER   BEACHES.  ■  151 

apart,  aud  thus  to  prevent  the  most  effective  friction  of  the  faces 
upon  one  another. 

To  the  action  of  cajiilhiry  attraction,  as  above  descrihcil,  is 
due  the  fact,  that,  when  tlic  division  of  rock  materials  to  the  state 
of  sand  is  brought  about,  all  or  nearly  all  the  erosion  due  to 
the  beating  of  the  fragments  togetlier  ceases.  Some  wearing 
is  accomplished  when  the  grains  are  caught  between  pebbles, 
and  so  come  between  upper  and  nether  millstones.  A  certain 
though  small  and  slow  decay  is  brought  about  by  chemical  ac- 
tion; l)ut  in  general  the  sand,  while  it  is  in  the  sea,  is  singularly 
well  preserved  fi'om  injury.  We  can  the  better  note  the  meas- 
ure of  this  preservation  by  observing  what  happens  to  the  sand 
which  comes  into  the  possession  of  the  wind.  In  this  condition 
there  is  nothing  to  keep  the  grains  apai't.  They  wear  rapidly, 
though  they  receive  no  such  blows  as  are  delivered  on  the  beach 
by  the  surf.  In  the  coui'se  of  a  few  miles  of  journey  the  sand 
in  the  dunes  is  more  worn  than  that  which  has  inoved  for,  it 
may  be,  a  thousand  miles  along  the  shore.  Thus  the  sand  of 
northern  Florida,  which  has  traveled  southward  from  the  region 
beyond  Cape  Hatteras,  is  not  more  roimded  than  much  which  is 
in  the  inner  or  landward  dunes  of  the  coast  within  sound  of  the 
ocean  waves. 

The  result  of  the  protection  against  wearing  which  is  afforded 
to  sand  gi'ains  by  the  water  which  surrounds  them  in  the  sea  is 
of  very  great  consequence  in  the  history  of  the  lands.  As  before 
remarked,  l)y  far  the  greater  part  of  the  marine  shore  lines  are 
bordered  by  sands.  Probably,  the  world  a])out,  over  nine  tenths 
of  coasts  are  fringed  by  such  beaches,  composed  of  practically 
indestructil)lo  materials.  Upon  these  bounds  the  ocean  waves, 
which,  when  armed  with  pebbles,  can  successfully  assail  the 
hardest  rock  cliffs,  l>reak  without  effecit.  Were  it  not  for 
these  indestructible  shields,  the  waves  would  long  ago  have 
reduced  the  land  areas  to  much  smaller  proportion  than  they 
now  exhil)it. 

Bamueh  Beaches. — The  function  of  sand  beaches  in  defend- 
ing the  land  from  the  assault  of  the  waves  makes  it  interesting 
to  note  in  more  detail  the  ways  in  which  these  lieaches  are 
formed  and  maintained  along  the  continental  shores.  The 
easiest  way  in  which  to  ajiproach  this  inquii-y  is  by  supposing 
that  the  coastal  region  of  the  southern  part  of  the  United  States 
should  be  elevated  in  a  geologically  smlden  manner,  so  as  to 


152  BEACHES  AND   TID.Ui   MAKSHES. 

bring  above  the  sea  a  part  of  the  contiueutal  shelf  which  is  still 
covered  by  the  oceau  waters. 

The  immediate  effect  of  elevating  a  seaboard  region  which  is 
fringed  by  the  characteristic  shaUows  of  a  continental  shelf  is  to 
bring  the  surf  line  against  an  unprotected  shore,  so  that  it  may 
attack  it  in  a  very  effective  way.  So  long  as  the  waves  are  of 
ordinary  height,  they  may  break  close  in  against  the  land,  and 
their  swash  will  proceed  to  cai'S'e  out  a  cUff ;  the  rocky  waste 
thus  formed  being  drawn  back  by  the  reflux  of  the  waves,  and 
serving  to  shallow  the  water  for  some  distance  from  the  shore. 
This  process  of  shoaling  will  also  be  favored  by  the  action  of 
the  waves,  which,  as  they  approach  the  land,  will  drag,  by  the 
friction  which  they  exercise  upon  the  bottom,  large  quantities 
of  sand  in  toward  the  coast  line.  TVheu  the  depth  of  the  water 
has  been  thus  considerably  diminished,  it  will  happen,  in  some 
great  storm,  when  the  waves  have  an  unusual  height,  that  they 
will  break  at  a  considerable  distance  from  the  land.  The  line  of 
the  surf  may  indeed  be  placed  some  miles  away  from  the  actual 
shore. 

As  soon  as  a  line  of  breakers  is  formed,  a  number  of  condi- 
tions combine  to  bring  about  the  formation  of  an  elevation  of 
the  bottom  at  the  point  where  the  waves  are  overtui'ned.  Each 
wave  in  succession  drags  a  certain  amount  of  sand  with  it,  this 
detritus  being  laid  down  when  the  wave  overturns  and  is  thus 
broken  up.  In  some  cases  it  may  come  about  that  the  upward 
gi-owth  of  this  elevation  takes  place  with  such  rapidity  that  in 
the  course  of  a  day  or  two,  in  which  heavy  seas  prevail,  the  ele- 
vation may  attain  to  near  the  surface  of  the  water.  If  it  hap- 
pen to  rise  from  the  level  of  the  sea,  the  permanence  of  the 
barrier  is  at  once  assured;  if  it  fall  short  of  that  height,  the 
lesser  waves  of  the  following  ordinary  weather  are  likely  to 
overrun  the  elevation,  and  to  scour  away  a  part  of  its  height. 
But  in  some  subsequent  great  storm,  the  waves  in  which,  on 
account  of  their  height,  have  to  break  along  the  shallow  line, 
the  ridge  is  pretty  sure  to  be  built  above  the  water  level.  "Wlien- 
this  height  is  attained,  a  portion  of  the  sand  brought  in  by  the 
waves  has  a  chance  to  become  dry,  and  thus  is  easily  moved  by 
tlie  wind.  In  this  condition  it  is  readily  driven  over  the  narrow 
ridge  into  the  water  of  the  lagoon  which  the  barrier  has  formed, 
or  it  may  accumulate  in  the  form  of  dunes.  As  time  goes  on, 
the  continued  accessions  of  sand,  drawn  in  from  the  sea  bottom 


.   INLETS.  153 

by  the  waves,  serve  to  widen  the  barrier,  which  in  the  course 
of  a  few  thousand  years  may  gi-ow  to  the  width  of  some  miles. 

"  Inlets."  —  The  barrier  beach  may,  wlieu  originally  formed, 
have  great  continuity.  Occasionally,  where  there  hapjion  to  be 
strong  headlands  with  deeper  water  off  their  faces,  the  Wall  of 
the  beach  may  come  in  contact  with  the  land ;  but,  as  it  is  shown 
by  many  instances,  the  narrow  island  of  the  reef  may  extend  in 
continuous  manner  for  the  distance  of  hundreds  of  miles  along 
the  shore.  Owing,  however,  to  the  fact  that  the  barrier  acts  as 
a  dam  to  hinder  the  land  waters  from  taking  their  natural  course 
to  the  sea,  it  is  sure  to  be  breached  by  outlets  from  point  to  point 
along  its  length.     Such  breaches  are  usually  miscalled  "  inlets." 

It  is  characteristic  of  those  l)reaches  which  give  exit  to  the 
river  waters,  that  they  are  formed  and  closed  in  a  somewhat 
curious  manner.  It  may  generally  be  observed  that  the  open- 
ing forms  near  the  point  where  the  barrier  joins  the  headland, 
and  that  year  by  year  the  opening  moves  along  the  si  lore,  the 
gap  filling  on  the  one  side  and  cutting  on  the  other,  until  it  at- 
tains the  next  headland  in  its  line  of  march.  Then  for  a  brief 
time,  while  the  river  waters  bank  up  in  the  lagoon,  the  breach  is 
closed,  again  to  open  at  the  point  where,  in  the  previous  case,  it 
was  seen  to  begin.  Tlie  reason  for  this  singular  marcliing  of 
the  inlets  on  a  barrier  beach  is  to  be  found  in  the  fact  that  along 
these  sand  walls  the  detrital  materials  joimiey  in  one  direction, 
which  is  determined  by  the  set  of  the  current  which  sweeps 
the  shore.  Thus  along  the  Atlantic  coast  from  Cape  Hatteras 
southward,  and  also,  though  in  a  less  determined  manner,  on  the 
more  northern  parts  of  that  shore,  there  is  a  southward-setting 
current,  which  makes  a  gradual  drift  of  sand  all  the  way  down 
to  Cape  Florida.  Hence  it  comes  about  that  the  sands  fill  in  on 
the  northern  side  of  the  inlet,  and  force  the  waters  continually 
to  widen  the  exits  on  their  south  l)anks, —  a  process  which  com- 
pels the  passage  to  move  down  tlie  coast.  As  each  headland 
somewhat  oljstructs  the  southward  march  of  the  sands,  the  bar- 
rier beach  is  ai)t  to  remain  lowest  immediately  south  of  where 
the  ridge  comes  against  the  projecting  part  of  the  shore ;  and 
so,  when  the  inlet  has  to  form  again,  the  breach  is  apt  to  occur 
at  that  point, — the  place  where  it  originally  formed. 

The  Lagoon  or  bay  between  the  barrier  beacli  and  the  main- 
land, being  originally  shallow,  and  receiving  accessions  of  detrital 
matter  from  the  rivers,  from  the  sand  blown  over  the  beacii,  and 


VA  BEACHES   AND   TID.AX,   MAKSHES. 

from  the  accumulations  of  organic  remains,  is  gradually  brought 
into  the  condition  of  a  swamp,  through  which  wander  the 
streams  whieh  convey  the  land  waters  to  the  open  ocean.  When 
this  state  is  attained,  the  detritus  borne  down  by  the  rivers  is 
again  deposited  beyond  the  coast  line,  where  it  serves  to  aid  in 
the  sliallowiug  process,  which  is  likely  in  time  to  lead  to  the 
formation  of  yet  another  barrier  beach.  Even  without  the  inter- 
vention of  river  sediment,  the  other  agents  which  accumulate 
sediments  on  the  sea  floors  are  likely  to  bring  about  a  measure 
of  shoaling,  which  results  in  the  formation  of  these  successive 
sand  reefs,  in  the  manner  above  described. 

Although  the  foregoing  account  as  to  the  formation  of  beach 
barriers  along  shores  which  have  the  characteristic  continental 
shelf,  shoaling  near  the  coast  line,  has  been  pre[)ared  as  a  gen- 
eral statement,  it  may  be  taken  as  an  account  of  the  steps  by 
whij?h  the  elongate  sand  islands  whieh  inclose  the  lagoons  and 
l)ays  of  the  region  south  of  Cape  Hatteras  and  north  of  Cape 
Florida,  as  well  as  those  along  the  northern  shores  of  the  Gulf 
of  Mexico  and  elsewhere,  have  been  formed.  By  consulting 
the  excellent  Coast  Survey  maps  of  the  Atlantic  shore  of  the 
United  States,  the  student  may  note  the  fact  that  there  is  an 
almost  continuous  water  "way  inclosed  by  these  wave-made 
islands,  extending  in  some  cases  for  the  distance  of  many  hun- 
dred miles.  Here  and  there  the  slightly  higher  parts  of  the 
land  have  formed  capes  with  such  a  depth  of  water  oft"  their 
faces,  that  the  barrier  beach  has  been  forced  into  contact  with 
their  shores;  but  so  inconsiderable  are  these  interrni>tii)ns,  that 
a  small  })oat  can,  with  infre(iuent  jjovtages,  )>e  navigated  from 
near  Norfolk,  Va.,  to  Bay  Biscayue,  in  southern  Florida.  It 
has  indeed  been  proposed  to  develop  this  natnral  water  way  into 
a  ship  canal,  which  would  aft'ord  a  safe  and  easy  route  for  vessels 
passing  along  this  dangerous  portion  of  the  continental  shores. 
__  CoEAL  Beaches.  —  On  certain  portions  of  the  ocean  shores 
within  the  tropics,  where  a  current  of  warm  water,  impelled  by 
the  trade  winds,  continuously  moves  in  against  the  coast  line,  those 
species  of  polyp  which  dwell  in  communities,  commonly  known 
by  the  name  of  corals,  are  developed  in  a  very  plentiful  way. 
These  compound  animals  are  common  on  the  sea  bottoms  even 
in  waters  as  far  north  as  Cape  Cod ;  but  only  where  the  species 
of  the  group  are  nomnshed  by  warm  currents,  such  as  often  flow 
in  upon  the  shores  and  shallows  of  the  seas  which  are  warmed  by 


COKAL,   BEACHES.  155 

a  nearly  vertical  sun,  do  these  creatm-es  gi'ow  in  sucli  numbers 
and  to  such  aggregate  bulk,  that  they  may  form  a  coast  line. 

It  is  characteristic  of  coral  beaches  that  nearly  all  the  sand, 
or  rather,  we  should  say,  the  finely  divided  matter,  of  which  they 
are  formed,  is  composed  of  the  skeletons  or  limestone  framework 
which  serves  to  supjiort  the  coral  animals  while  they  are  in  the 
living  state.  This  material  is  mingled  with  the  debris  of  shells, 
and  often  in  large  measure  with  the  limestone  coverings  of  the 
small  Foruminifcra.  While  the  corals  are  living,  they  are  admi- 
ral)ly  adjusted  to  the  assault  of  the  waves  in  such  a  mannei-  that 
the  sea  is  practically  unable  to  damage  their  communities.  It  is 
only  when  a  colony  dies  in  whole  or  in  part  that  the  waves  are 
fairly  able  to  make  use  of  its  fragments  in  building  a  beach.  In 
fact,  beaches  of  this  nature  depend  for  their  growth  and  nuiin- 
tenance  almost  entirely  on  the  work  of  extracting  limy  nuitter 
from  the  sea,  which  the  coral  animals  accomplish  in  a  second- 
hand way  l)y  consuming  marine  plants  or  other  animals  which 
have  fed  upon  that  source  of  supjily. 

The  student  who  would  obtain  a  clear  notion  of  coral  beaches 
should  visit  some  shores  of  that  description,  such  as  may  be 
found  along  the  Keys  of  southern  Florida  or  in  the  islands  of 
the  Bermudas.  Selecting  any  poi'tion  of  the  strand  which  faces 
the  open  sea,  he  will  observe  that  the  beach  is  covered  by  a  layer 
of  whitish  powdery  rock,  the  grains  of  which  are  more  rounded, 
and  generally  more  variable  in  size,  than  are  the  bits  of  ti'U(>  sand 
of  an  ordinary  shore.  Carefully  examining  the  material,  he  will 
perceive  that,  except  that  there  is  here  and  thei-e  a  bit  of  pumice 
or  volcanic  lava  blown  so  full  of  bubbles  that  it  becomes  light 
enough  to  float,  all  the  debris  of  the  shores  is  of  oi-ganic  origin. 
On  the  landward  side  of  the'  beach  he  will  commonly  find  a  low 
cliff,  cut  either  in  the  older  part  of  the  reef,  which  has  been  lifted 
up  from  the  sea  by  the  upward  movement  of  the  land,  or  in  a 
dune-like  accumulation  composed  of  tiuy  bits  of  coral  which  have 
V)lown  in  from  the  strand  when  it  dries  in  the  hot  sun.  Whetlior 
this  part  of  the  reef  which  is  exposed  to  the  air  is  dune  or  ele- 
vated bottom,  it  is  always  easy  to  note  the  fact  that  the  rock 
material  is  exposed  to  a  rapid  solution  by  the  rain  water.  The 
result  is  that  the  dunes  never  attain  any  great  height;  moreover, 
they  never  march  far  inland,  in  the  manner  of  sand  dunes,  for 
the  reason  that  the  limestone  grains  speedily  become  consolidated 
into  a  tolerably  firm-set  rock. 


; 


156  BEACHES  AXD  TID.\1,  MAKSHES. 

Looking  to  the  seaward  at  low  tide,  the  observer  may  note  in 
the  hollows  of  the  surf  the  protruding  tops  of  the  living  coral 
communities,  which  never  attain  a  height  above  the  i)lane  of 
ordinary  low  tide,  and  which  serve  to  maintain  the  large  supply 
of  matter  which  is  continually  being  gi'ound  up  by  the  action  of 
the  waves. 

In  most  cases  the  coral  shore  lies  upon  a  fringing  reef,  sepa- 
rated from  the  mainland  by  a  shallow  landlocked  basin  in  which 
a  host  of  frailer  coral  commimities  and  other  delicate  marine 
creatures  develop.  These  landlocked  forms  afford  a  great  deal 
of  limestone  sediment  in  the  form  of  mud,  which  is  carried  out 
to  the  front  of  the  beach  by  the  tidal  currents.  In  some  cases 
the  amount  of  this  organic  deliris  is  so  large  that  it  accumulates 
in  the  form  of  a  considerable  delta  at  the  seaward  end  of  the 
channels  which  connect  the  lagoons  with  the  open  water. 

In  the  tropical  oceans,  and  even  in  higher  latitudes  which 
are  affected  liy  warm  currents,  coral  islands  frequentlj'  abound 
which  afford  very  interesting  organic  beaches.  Islands  of  this 
nature  are  most  abundant  in  the  Pacific  and  Indian  oceans,  but 
they  also  occur  in  the  Atlantic  basin  along  the  line  of  the  eastern 
Antilles.  Tliey  constitute  the  Bahamas,  the  greater  part  of  the 
islands  or  Keys  of  Florida,  and  the  beautiful  archipelago  known 
as  the  Bermudas.  These  oceanic  coral  islands  commonly  have 
an  annular  or  ringlike  shape,  inclosing  a  1  )asin  or  lagoon.  Some- 
times the  ring  is  comj^osed  of  a  single  island,  through  which 
there  is  but  one  breach  connecting  the  inner  and  outer  water. 
In  other  instances  the  ring  is  formed  l)y  many  small  isles,  with 
shallow  water  ways  between  them.  Coral  deposits  of  this  form, 
known  as  atolls,  present  very  beautiful  beaches  of  organic  rock, 
that  on  the  outer  side  being  wide,  and  the  seat  of  a  heavy  grind- 
ing action  which  the  waves  inflict  on  the  dead  coral ;  while  the 
lieach  bordering  the  lagoon,  of  which  the  shallow  waters  are 
rarely  more  than  a  mile  or  two  in  diameter,  forms  a  delicate 
strand  of  no  great  width,  for  the  reason  that  tlie  waves  have 
not  nn;ch  ])ower.  From  the  oiiter  beach  the  storm  winds  in  dry 
weather  sweep  a  good  deal  of  powdered  rock  into  rudely  shapea 
dunes,  which,  being  comi^osed  of  fertile  earth,  often  support  a 
luxuriant  vegetation  of  palms  and  other  tropical  plants.  The 
combinations  of  beaches,  and  their  products  the  wind-made  hills, 
make  the  atoU  the  most  singular  geographical  feature  of  the 
tropical  seas. 


u 


MARINE   MARSHES.  157 

It  is  chai-acteristic  of  coral  beaches  that  the  materials  of 
which  they  are  composed,  unlike  those  of  ordinary  shores,  are 
readily  taken  into  solution,  and  in  that  state  may  be  borne  away 
by  the  currents  to  any  distance..  As  these  reefs  can  only  be 
found  where  ocean  currents  moving  with  considerable  velocity 
come  in  contact  with  shallows  or  shores,  the  water  which  bathes 
them  is  always  in  motion,  and  so  bears  off  the  dissolved  matter. 
Notwithstanding  the  constant  robljery  of  their  matei-ials,  which 
is  effected  by  the  solving  process,  the  coral  beaches  often  widen 
with  great  rapidity ;  the  contributions  of  their  debris  which  are 
made  to  the  ocean  floor  are  great  in  quantity  as  well  as  widely 
distributed;  and  the  powdei-ed  waste  which  is  blown  to  the 
landward  by  the  winds  is  often  sufficient  to  cover  consideral)le 
extents  of  country. 

A  capital  instance  showing  the  constnicting  efficiency  of  reef- 
building  corals  may  be  seen  in  southern  Florida,  where  the  outer 
or  southward  third  of  the  great  promontory  owes  its  construction 
to  the  development  of  successive  fringes  of  coral  gi'owth  on  the 
beaches  formed  of  the  debris  of  these  reefs,  and  of  the  detrital 
matter  blown  from  the  beaches  into  the  shallows  between  them 
and  the  mainland. 

Marine  Marshes. — Closely  related  to  the  work  which  is 
effected  by  coral  reefs  is  the  organic  result  accomplished  by 
other  groups  of  living  beings  along  all  the  shores  of  the  world. 
We  have  already  noted  the  fact  that  in  the  beach  the  results  of 
marine  action  lead  to  the  construction  of  a  broad,  gently  sloping 
shelf,  extending  from  the  shore  to  a  considerable  depth  of  water. 
This  slightly  declining  part  of  the  sea  floor  affords  an  admirable 
site  for  the  development  of  a  great  array  of  species  both  of  ani- 
mals and  plants.  Owing  to  the  shallowness  of  the  water,  a  share 
of  the  sunlight  passes  through  the  fluid  to  the  liottom.  The 
grinding  action  which  takes  place  in  the  waves  bi'ings  much 
mineral  matter  and  organic  material  into  the  condition  where 
it  readily  becomes  fit  to  support  the  species  which  dwell  in  these 
shoals.  The  undertow  and  other  currents  transport  this  suste- 
nance to  the  waiting  throng  of  lieings.  In  these  and  other  ways 
the  undersea  portion  of  the  beach  becomes,  of  all  the  water- 
covered  areas,  the  fittest  seat  of  life. 

Where,  as  is  the  case  on  most  sandy  shores,  and  also  behind 
those  coral  reefs  which  fringe  the  mainlands,  there  are  inclosed 
areas  of  shallow  water,  we  find  another  realm  extremely  well 


158  BEACHES  AND  TIDAL  MARSHES. 

suited  to  organic  development.  As  before  noted  in  the  case  of 
coral-reef  lagoons,  these  embayed  waters  are  admirably  suited 
to  the  gi-owth  of  marine  species.  Among  the  animals,  the  bivalve 
Molluscii,  particularly  the  oysters,  find  these  sites  very  well 
suited  to  their  needs.  They  often  build  deposits  composed 
almost  altogether  of  their  shells,  having  a  dejith  of  many  feet,  and 
a  horizontal  extension  of  many  square  miles  in  area.  In  these 
embayed  waters  many  species  of  crustaceans  flourish,  and  at 
their  death  give  their  skeletons  to  the  accumulation  which  grad- 
ually shallows  the  water.  In  this  manner  the  areas  fenced  in  by 
barrier  beaches  become  floored  with  sediments,  which,  so  far  as 
their  chemical  composition  is  concerned,  are  admirably  fitted  for 
agricultural  purposes.  A  large  part  of  the  fertile  land  of  Hol- 
land has  been  won  to  tillage  by  completing  the  natui-al  beach 
barriers  which  separate  the  fertile  ground  from  the  sea,  the 
water  from  the  fields  being  removed  by  pumps. 

When  the  lagoons  behind  the  sand  beaches  have  become  shal- 
lowed to  the  dej^th  of  ten  or  twenty  feet,  certain  low-grade  flower- 
ing plants,  mostly  of  grasslike  form,  begin  to  convert  the  areas 
into  manne  marshes, — wide  savannas  which  are  covered  bj'  the 
sea  for  but  an  hour  or  two  a  day,  during  the  time  of  high  tide. 
The  process  by  which  the  marsh  growth  takes  place  is  very 
interesting. 

A  number  of  land  plants  have  modified  their  original  specific 
characteristics  so  that  they  are  enabled  to  dwell  in  contact  with 
or  even  under  the  sea,  the  salts  of  which  are  deadh'  to  almost 
all  vegetable  species.  Among  these,  the  most  interesting  is  that 
known  as  the  eel  grass,  which,  though  a  fiowei-ing  plant,  never  lifts 
its  form  above  the  surface  of  the  water.  This  species  will  take  root 
in  the  embayed  waters  wherever  the  bottom  is  soft,  and  less  than 
twelve  feet  in  depth  at  low  tide.  Within  the  close-set  stems 
dwell  a  host  of  marine  creatures;  moreover,  the  network  en- 
tangles drifting  sediments;  the  two  actions — that  arising  from 
the  death  of  organic  life,  and  that  from  the  floating  debris  which 
is  caught,  and  brought  to  the  bottom  — serving  rapidly  to  shoal 
the  bottom  of  the  lagoon.  A  number  of  other  plants,  mostly 
grasslike  forms,  begin  to  grow  on  the  nuid  flats  formed  between 
the  eel-grass  banks  and  the  shore.  These  species,  which  require 
to  be  above  the  water  level  for  the  most  of  the  day,  produce  a 
very  dense  mat  of  vegetation  bj'  weaving  their  tough  roots  to- 
gether, thus  forming  a  mass  which  only  heavy  waves  can  break 


MAKINE   MARSHES.  139 

up.  lu  this  manner  the  construction  of  the  marine  marsh  is 
begun  around  the  margins  of  the  water  field. 

When  the  waters  inclosed  Ly  a  barrier  Vjeach  have  been 
brought  into  the  state  of  a  marine  niarsli,  the  area  can,  as 
experience  shows,  in  most  cases  be  readily  won  to  the  uses  of 
agriculture.  Wherever  the  rise  and  fall  of  the  tide  is  eight  feet 
or  more,  it  is  possible  so  to  arrange  dams,  at  the  point  where 
the  sea  water  enters,  that  the  level  of  tlu^  marsh  may  be  kept 
permanently  above  the  sea;  then,  by  means  of  appropriate 
ditchings,  and  by  removing  the  tough  mat  of  grass  and  roots, 
rich  and  very  enduring  soils  are  made  ready  for  tillage.  Exper- 
iments made  on  the  coasts  of  New  England  and  elsewhere  show 
that  lands  thus  won  from  the  sea  are  fitted  to  a  great  range 
of  crops,  and  can  be  tilled  for  many  years  without  reijuii-ing 
mani;ring. 

Where  the  tides  rise  to  a  gi-eat  height,  as  in  the  region  about 
the  Bay  of  Fundj',  the  strong  currents  created  by  the  watei-s  which 
enter  and  leave  the  embaymeut  sweep  with  them  g)-eat  (piantities 
of  mud.  In  such  regions  the  people  have  learned  to  constnict 
artificial  dams  separating  the  mud  flats  from  the  sea,  the  barriers 
being  provided  with  openings  for  the  passage  of  the  tidal  waters. 
These  waters,  entering  the  artificial  lagoons  laden  with  sediment, 
are  retained  in  the  area  until  they  have  laid  down  their  burden. 
When,  by  this  process  of  deposition,  the  bottom  of  the  inclosed 
space  has  been  brought  to  near  high-tide  mai-k,  the  sea  is  barred 
out,  and  the  new-made  land  is  ditched  and  brought  into  the  con- 
dition of  profitable  fields. 

Although  in  this  country  the  long-continued  abvmdance  of 
good  land  on  the  frontiers,  which  might  be  had  almost  for  the 
asking,  has  kept  peoj^le  from  paying  much  attention  to  the 
class  of  lands  which  have  afforded  the  agricultural  wealth  of 
Holland,  the  time  is  soon  coming  when  the  mai'ine  marshes 
formed  behind  the  barrier  beaches  along  the  Atlantic  coast  will 
be  brought  into  condition  to  serve  the  uses  of  man.  It  seems 
likely  that  somewhere  near  twenty  thousand  square  miles  of 
extremely  fertile  soil  will  thus  be  gained  to  the  service  of  our 
people  when  they  have  applied  the  methods  of  im]irovement 
which  have  been  so  successfulh'  followed  in  the  districts  about 
the  mouth  of  the  Khine. 

Although  the  grasslike  plants  do  the  most  of  the  work  of  win- 
ning the  shallows  from  the  sea  in  the  manner  above  described,  a 


160  BEACHES  AND  TIDAL  MARSHES. 

similar  end  is  effected  in  the  tropical  parts  of  the  world  by  the 
growth  of  the  peculiar  group  of  trees  kuowu  as  jiianffrores.  All 
other  forms  of  arboreal  vegetation  except  the  uiaugroves  are 
imable  to  tolerate  auy  considerable  contact  with  sea  water ;  but 
these  trees,  of  which  there  are  a  number  of  species  in  different 
parts  of  the  world,  have  varied  their  habits  and  their  structure 
in  a  remarkable  way,  and  have  thus  become  competent  to  meet 
the  peculiar  conditions  which  they  have  to  encounter  in  the 
lagoon  behind  the  barrier  reefs  formed  by  the  coral  or  sand 
beaches  of  warm  regions.  Beginning  on  the  shore,  the  mangrove 
establishes  its 'crown  above  the  level  of  high  tide.  From  this 
crown  or  junction  point  of  stem  and  roots  there  extend  off 
toward  the  sea  long  runner-like  jiroeesses,  which  grow  down- 
ward into  the  water  until  they  attain  the  bottom,  and  there 
take  root.  From  the  upper  part  of  these  runners  new  stems 
arise;  and  the  process  may  be  continued  until  wide  lagoons 
become  covered  with  a  low,  dense  forest,  beneath  which  the  tide 
may  ebb  and  flow  until  the  falling  leaves  and  twigs,  together 
with  the  remains  of  animals,  have  filled  up  the  interspaces.  In 
this  way  the  mangroves  win  to  the  conditions  of  marsh  great 
areas  of  embayed  waters,  and  thus  complete  the  work  of  barring 
out  the  sea  which  is  begun  in  the  formation  of  barrier  beaches. 

The  foregoing  paragrajjlis  may  serve  to  indieat(>  in  a  general 
way  something  of  tlie  more  important  work  in  relation  to  or- 
ganic life  which  is  brought  about  through  the  growth  of  beaches 
and  the  work  which  is  done  upon  them.  This  work  consists  in 
part  in  the  formation  of  shallows  next  the  shore,  which  afford  a 
favorable  site  for  the  development  of  living  forms ;  in  the  grind- 
ing-up  of  organic  waste  to  a  state  in  which  it  can  readily  be 
transported  liy  the  waters  to  the  creatures  which  it  is  to  feed; 
and  in  the  development  of  extensive  shallow  landlocked  basins, 
which  by  their  conditions  favor  the  growth  of  a  great  range  of 
animals  and  plants.  Having  thus  traced  in  outline  the  inore  im- 
portant relations  of  beaches,  we  must  now  turn  our  attention  to 
certain  detailed  features  in  these  structures  and  their  distribution. 

Composition  of  Sand  Be.\ches. — It  should  be  noted,  that, 
while  sand  beaches  are  extensively  developed  along  the  shores 
of  all  the  continents,  they  rarely  appear  in  anything  l)ut  the 
most  attenuated  form  on  the  smaller  islands  which  exist  at  dis- 
tances of  more  than  a  few  miles  from  the  shore,  or  which  are 
surrounded  by  deep  water.     On  such  insular  lands  the  ground- 


COMPOSITION   OF   SAXD   BEACHES.  161 

Up  rock  waste  which  goes  to  form  sand  beaches  is  likely  to  be 
swept  away  from  the  shores,  the  amount  remaining  being  insuf- 
ficient to  aflford  characteristic  beaches  of  this  nature.  On  the 
seaward  faces  of  the  continent  the  long-continued  shoivs  afford 
an  opportunity  for  the  arenaceous  material  to  journey  for  great 
distances,  and  to  be  accumulated  on  those  portions  of  the  coast 
toward  which  it  is  impelled  by  the  prevailing  direction  of 
the  wind  and  the  current.  Thus  on  the  eastern  coast  of  North 
America  the  sand  derived  from  the  wearing  of  the  cliff  or  bluff 
shores  which  are  wasting  under  the  action  of  the  sea  (as  those 
along  the  coast  of  New  Jersey)  journeys  southward  for  a  great 
distance.  It  is  impelled  in  this  direction  because  the  average 
direction  in  which  the  waves  nm  in  from  the  sea  is  from  the 
east,  while  the  trend  of  the  shore  is  southwesterly.  The  result 
is  that  the  sands  march  down  the  shore,  impelled  by  a  current 
which  is  inflected  to  the  south  by  the  trend  of  the  shore. 

The  reader  can  by  a  simple  experiment  illustrate  the  manner 
in  which  such  a  current  is  formed.  Taking  an  ordinary  l^asin 
of  water,  the  breath  from  the  lips  can  be  used  to  form  wavelets, 
which  may  be  made  to  break  against  a  straight-edged  1)ai-rit>r. 
Using  small  floats,  it  can  be  noted  that  the  resulting  current  sets 
down  the  barrier  in  the  direction  in  which  it  inclines;  that  is, 
on  the  side  of  the  obtuse  angle  between  the  axis  of  the  air 
stream  and  the  resulting  waves  and  the  opjiosiug  margin. 

In  its  journeys  down  the  long  coast  between  Long  Island, 
New  York,  and  Florida,  the  moving  sand,  where  it  passes 
the  mouth  of  a  considerable  river,  is  i>retty  siu'e  to  be  thrust 
for  a  distance  out  to  sea  on  the  continental  shelf.  From  this 
excursion  to  the  seaward  it  is,  howevei",  returned  by  the  action 
of  the  waves,  and  so  comes  again  to  the  shore,  or  the  verj'  shallow 
water  next  it,  and  is  thus  free  to  go  farther  to  the  southward. 
As  both  the  eastern  and  western  shores  of  North  America  exten<l 
obliquely  to  the  run  of  the  waves,  which  come  on  the  one  side 
from  the  east  and  on  the  otlicr  side  from  tlie  west,  there  is  a-ii  evi- 
dent tendency  on  both  the  Atlantic  and  Pacific  coasts  for  the 
sands  to  work  to  the  soi;thward.  This,  liowever,  is  much  more 
conspicuous  on  the  eastern  side  of  the  continent. 

We  shall  next  consider  some  interesting  details  whicli  may  be 
here  and  there,  though  not  continuously,  obsei'ved  along  the 
beach  lines  wherever  they  are  exhibited  in  their  normal  form. 
First  among  these  we  may  note  the  materials  found  along  the 


162  BEACHES  AND  TID.\I.  MARSHES. 

straud  which  liave  not  been  derived  from  the  wearing  of  the 
hind  or  from  the  impcn-tation  of  pebbles  or  shells  brought  in  by 
the  scouring  action  of  the  waves  from  the  neighboring  shallows. 

First  among  the  list  of  casual  contributions  to  the  beaches 
we  should  perhaps  reckon  the  debris  from  the  arts  of  man.  This 
consists  not  only  of  ordinary  wrecks,  which  find  their  way  to  the 
beaches,  but  of  a  quantity  of  other  materials  derived  tVom  the  arts. 
Noting  first  the  wrecks,  we  observe  that  where  a  ship  goes  ashore 
on  a  bowldery  beach,  its  framework,  however  strong,  is  likely  in  a 
few  years  to  be  beaten  to  pieces  by  the  hard  strokes  which  the 
stones  deliver  when  set  in  motion  by  the  waves.  If  it  be  a  tim- 
ber vessel,  the  fragments  are  ground  to  fine  bits,  and  float  away. 
If  the  craft  be  of  iron  or  steel,  the  oxidizing  action  of  the  sea 
water,  together  with  the  wave  work,  insures  a  slower  j-et  com- 
plete destruction.  Rarely  is  any  part  of  the  wi-eck  built  into 
the  submerged  portion  of  the  beach. 

It  is  otherwise  where  a  ship  is  wrecked  upon  a  sandy  strand. 
Because  there  are  no  stones  to  strike  lieaAy  blows  in  times  of 
storm,  the  firmer  parts  of  the  vessel  may  endure  in  a  little- 
Avorn  state  for  many  years.  In  some  cases,  hewn  timbers  ex- 
posed to  the  stroke  of  a  powerful  surf  will  keep  their  scpiared 
shape  for  a  decade  or  more.  If  they  are  below  the  level  of  high 
tide,  they  are  apt  to  receive  some  protection  from  the  l)arna- 
cles,  shellfish,  and  other  organic  forms  which  find  a  lodgment 
upon  them.  Moreover,  the  whirling  currents  formed  when  the 
waves  break  against  the  hulk  ai-e  likely  to  excavate  the  sand 
beneath  the  bottom,  and  thus  allow  the  remains  of  the  craft 
gradually  to  settle  down  into  the  loose  material ;  so  that  in  the 
course  of  a  few  years  the  framework  of  a  considerable  ship  may 
disappear  from  view.  If  the  beach  goes  on  widening  (a  pro- 
cess which  is  apt  to  take  i)lace),  the  vessel  may  in  time  come  to 
lie  quite  a  distance  inward  from  the  margin  of  the  water ;  there 
it  may  lie  hidden,  unless  some  whii-ling  action  of  the  wind,  such 
as  makes  and  unmakes  dunes,  strii)S  the  covering  away.  A  sec- 
tion across  any  one  of  the  wide  beaches  of  Europe,  which  has 
been  receiving  wi'eeks  for  two  thousiiiid  years  or  more,  might 
well  disclose  a  succession  of  castaway  vessels  dating  from  the 
beginning  of  the  seafaring  art  to  the  present  day,  lying  one 
beyond  another  to  the  seaward  in  the  order  of  their  antiquity. 

Along  almost  all  shores  of  the  open  sea,  the  debris  of  other 
human  arts  exceeds  in  (luantitv  that  which  comes  from  wrecks 


COMPOSITION   OF   SAND   BEACHES.  1G3 

oecurring  on  the  shore.  The  range  and  variety  of  this  del>ris 
which  bears  the  impress  of  the  hand  of  man  are  exceedingly 
gi-eat.  On  ahuost  every  sandy  lieach  in  New  Enghmd  the 
trained  observer  can  find  in  a  few  minutes'  walk  fragments  of 
shaped  wood  which  have  evidently  drifted  from  the  tropics,' 
borne  northwardly  by  the  Gulf  Stream,  and  driven  away  from 
its  surface  by  the  winds  which  blow  shoi-eward  over  that  cui-- 
rent.  Along  the  coast  of  Fk)rida  it  is  common  to  find  logs  of 
mahogany  hewn  into  shape  on  the  Imnks  of  rivers  in  South 
America  and  Central  America.  So  consid(>rable  is  the  amount 
of  wood  carried  northward  by  the  (xulf  Stream,  that  the  people 
of  far-off  Iceland  obtain  their  supplies  of  such  material  from 
the  drift  which  comes  upon  their  shores.  Thus  iml:)edded  in  an 
extending  sand  beach  we  may  find  the  more  solid  parts  of  trees 
which  have  journeyed  from  the  Equator  to  the  Arctic  Circle. 

Yet  another  curious  element  in  the  composition  of  the  sand 
beaches  is  the  volcanic  pumice,  which  i>lentifully  finds  its  way 
in  ocean  currents  from  one  sea  to  another,  and  which  naturally 
di'ifts  to  the  shores.  In  almost  aU  volcanic  eruptions  of  a  high 
order  of  intensity,  the  (juantity  of  this  lava,  so  filled  with  gas 
and  steam  vesicles  that  it  will  float,  is  very  large. 

When  pumice  comes  to  the  sea,  it  is  capable  of  floating  for  a 
very  long  time.  Unless  it  becomes  weighted  down  by  the  growth 
of  animals  and  plants,  the  bits  are  apt  to  find  their  way  to  the 
shores.  Inspection  of  the  sand  beaches  along  the  Atlantic  coast 
of  the  United  States  shows  that  this  puraiceous  matter  is  an  im- 
portant element  in  the  composition  of  these  strands.  It  seems 
likely  that  any  cubic  yard  of  the  sand  from  the  shores  which  face 
the  open  sea  will  reveal  recognizable  fragments  of  this  nature, 
though  the  greater  part  of  the  bits  will  be  of  small  size. 

Coming  U])on  peblily  beaches,  fragments  of  pumice,  because 
of  their  frail  natui'e,  are  (juickly  ground  to  unrecognizalde  pow- 
der. On  sandy  shores,  although  the  material  is  broken  up  by  the 
action  of  the  waves,  the  process  of  conmiinution  goes  on  more 
slowly.  As  might  be  expected,  the  amount  of  pumii-e  which 
comes  to  the  shores  varies  greatly  on  different  parts  of  the  coast. 
Thus  along  the  shore  of  Florida,  from  Bay  Biscayno  north- 
ward to  Ju])iter  Inl(4,  the  writer  has  found  fragments  of  pumice 
more  plentiful  than  on  any  other  portion  of  our  shores. 

Peculiar  Features  in  Beach  Structure. — Having  gained 
a  general  idea  of  beach  structure,  the  student  should  now  notice 


IG-t  BEACHES  AND  TIDAL  MARSHES. 

certain  peculiar  features  whicli  may  lie  observed  ou  the  surface 
or  in  the  interior  of  these  acciuuulations. 

The  most  interesting  marks  which  may  be  noted  on  the  shore 
are  those  which  are  formed  by  the  movements  of  the  water  as  it 
is  impelled  by  the  waves.  These  are  of  a  very  varied  nature. 
Selecting  any  pebbly  beach  where  the  stones  are  prevailingly  of 
small  enough  size  to  be  readily  tossed  about  by  the  waves,  the 
observer  will  note  that  at  almost  aU  times,  but  especially  after  a 
heavy  storm,  the  slope  from  the  high-water  line  downward  is 
scalloped  in  a  ciu'ious  manner.  From  the  level  beyond  the 
waves,  ridges  tapering  outwardly  extend  down  the  incline,  it 
may  be,  for  a  distance  of  from  ten  to  fifteen  feet  or  more,  and  a 
height  of  from  a  few  inches  to  two  or  three  feet.  Between  these 
ridges,  which  taper  toward  their  k)wer  and  outer  parts,  there  are 
small  wedge-shaped  embay ments,  which  at  the  outer  edge  of  the 
ridges  may  be  from  two  or  three  feet  to  fifteen  or  twenty  feet 
wide,  tajieriug  thence,  like  the  section  of  a  rather  pointed  cone 
which  is  obtuse  at  the  apex,  to  the  edge  of  high  water.  These 
scallops  may,  luider  favorable  conditions,  be  traced  in  orderly 
and  uniform  succession  along  miles  of  shore. 

It  seems  to  the  wi-iter  that  these  scallops  are  formed  about  as 
follows :  In  a  time  of  storm  the  inner  edge  of  the  swash  line  formed 
by  the  body  of  water  which  sweeps  up  and  down  the  beach  has  a 
very  indented  front,  due  to  the  fact  that  it  is  shaped  by  a  criss- 
cross action  of  many  different  waves.  As  these  tongues  run  up 
the  beach  and  strike  the  pebbles,  they  push  them  back  so  as  to 
make  a  slight  indentation  where  each  tongiie  strikes.  As  the 
water  goes  back,  it  piUls  out  the  fine  material,  but  does  not 
withdraw  the  pebbles.  The  next  stroke  of  the  splashing  water 
then  finds  a  small  bay,  the  converging  horns  of  which  slightly 
heap  uji  the  fluid,  making  the  stroke  a  little  harder  in  the  cen- 
ter of  the  tongue,  and  excavating  the  bottom  of  the  bay  still 
further.  As  the  reentrant  gi'ows  larger,  and  the  tide  rises 
higher,  the  water,  as  it  runs  up,  forms  a  small  wave,  which 
breaks  on  the  shore  of  the  recess,  and  casts  the  pebbles  more 
into  the  form  of  a  ridge.  This  action,  continuing  for  some 
hours  before  the  tide  turns,  serves  to  shape  the  embaymeut. 

It  shoiild  be  carefully  noted  that,  when  the  swaying  waters 
rush  up  into  the  shore  scallops,  the  converging  walls  of  these 
indentations  deepen  the  current,  and  add  to  the  efficiency  of  its 
movements, — a  ^Jrocess  which  is  essentially  like  that  which  is 


ELEVATED  OE  DEPRESSED  BEACHES.  105 

brought  about  wlieu  an  ordinary  wave  enters  into  a  recess  of 
the  cliff,  or  the  tidal  undulation  is  crowded  into  an  indentation 
such  as  th(3  Buy  of  Fundy. 

Reference  has  been  made  to  the  fact  that  the  water  from  tlie 
laud  emerges  through  the  upper  part  of  the  beach.  If  the  quantity 
is  large,  it  may  happen  that  the  fmtflow  is  sufBeient  to  keep  the 
grains  of  the  debris  some  distance  from  one  another.  In  this 
case  quicksands  are  formed,  wliich  may  be  inconvenient  or  even 
dangerous  to  the  unwary  explorer.  Quicksands  are  of  relatively 
rare  occurrence  along  the  seashores :  they  are  more  abundant  on 
the  beaches  of  rivers,  where  the  conditions  favor  the  escape  of 
springs  upward  through  the  accumulations  of  sand. 

Here  and  there,  where  waters  from  the  lagoons  behind  the 
beaches  have  made  fresh-cut  channels,  the  observer  may  note 
the  peculiar  form  exhibited  by  the  beds  or  layers  of  which  the 
beach  is  composed.  He  will  see  that  in  place  of  the  orderly  suc- 
cession of  beds  which  he  may  have  noticed  in  ordinary  stratified 
rocks,  which  in  almost  all  cases  have  been  formed  on  st-a  bot- 
toms away  from  the  shores,  the  beach  strata  are  considerably 
inclined,  and  that  each  layer  or  group  of  layers  is  apt  to  l)o  inter- 
sected by  other  layers  lying  at  different  angles.  Tliis  tangled 
structure  is  recognized  by  geologists  as  a  characteristic  mark 
of  beach  accumulation.  It  somewhat  resembles  the  layers 
foi'med  in  dunes  and  those  built  in  deltas.  It  will  be  worth 
while  for  the  student  to  work  out  these  differences,  if,  as  is  often 
the  case,  the  sand  beaches  which  he  is  studying  afford  oj^por- 
tunity  for  such  inquiries. 

Elevated  or  Depressed  Beaches. — We  have  now  completed 
the  outline  description  of  the  conditions  which  determine  the 
formation  of  beaches.  There  remain,  however,  many  minor 
yjoints  of  much  interest,  which  should  be  set  forth  in  order  to 
complete  the  account  of  these  interesting  features.  First  of 
these  we  may  note  the  elevated  or  depressed  beaches  formed 
along  shore  lines,  which  have,  since  their  i)eriod  of  activity,  been 
lifted  above  or  lowered  beneath  the  surface  of  the  waters. 

Along  nearly  all  the  coast  lines  which  have  been  attentively 
examined  by  the  students  of  coast  phenomena,  it  has  been  ob- 
served, that,  at  various  heights  above  the  present  sea  level, 
there  are  more  or  less  evident  remains  of  ancient  sea  beaches. 
Thus,  scarcely  any  portion  of  the  Atlantic  coast  of  the  United 
States  has  failed  to  yield  evidence  of  this  nature.     Geneivilly 


lot)  BEACHES   AND   TIDAL   MARSHES. 

speakiug,  marks  of  this  contact  of  the  sea  aud  laud  duviug 
foiiner  adjustments  of  level  are  most  conspicuous  at  heights  of 
less  than  one  hundred  feet  above  the  present  shore;  but  in  many 
cases  they  may  be  indistinctly  observed  at  several  times  that 
elevation.  It  will  be  readily  understood  that  the  liigher  a  beach 
is  in  general,  the  longer  the  time  dui-ing  which  it  has  been  sub- 
ject to  the  agents  of  destruction — the  rain,  the  friist  and  wind, 
as  well  as  the  cutting  of  the  streams — which  tend  to  destroy  its 
original  form.  It  is  therefore  rarely  the  case  that  we  can  definitely 
trace  the  position  of  shore  lines  which  were  formed  during  the 
earlier  geological  ages  and  afterward  elevated  into  the  air.  In 
fact,  all  the  important  raised  beaches  which  are  well  known  are 
of  geological  age  and  date. 

Although  the  course  of  the  land  movements  is  generallj' 
upward,  it  not  infrequently  happens  that  the  downward  settling 
or  tilting  of  the  laud  carries  the  sea  margin  below  its  original 
l)Osition.  Such  accidents  can  rarely  be  traced,  except  by  in- 
direct evidence.  The  slope  of  the  beach,  or  even  the  character- 
istic ridge  of  a  sand  barrier,  is  likely  to  be  obliterated  by  the 
dragging  action  of  the  waves.  It  is  sure  to  be  leveled  over  by 
deposits  of  detritus,  so  that  its  form  cannot  be  traced  by  the 
sounding  lead.  It  is  only  where  steep  sea  cliffs  have  been 
lowered  beneath  the  water  that  we  can  expect  to  find  any  evi- 
dence by  soundings  that  a  recently  formed  shore  line  has  been 
depressed  beneath  the  siu-face  of  the  ocean.  All  along  the  At- 
lantic coast,  from  Newfoundland  to  Florida,  there  are  abundant 
exidences  afforded  by  submerged  forests,  which  go  to  show  that 
the  shore  line  has  recently  been  much  farther  out  to  sea  than 
it  is  at  present.  Other  proofs  of  the  same  general  nature  are 
afforded  by  the  extent  to  which  river  valleys  excavated  by 
stream  action  have  been  invaded  by  marine  waters.  These  con- 
siderations, though  more  evident  to  the  trained  geologist  than 
to  the  beginner  in  the  science,  may  be  taken  to  prove  a  subsid- 
ence of  the  Atlantic  coast  line,  or  at  least  a  relative  gain  in  the 
height  of  the  sea  waters,  which  has  brought  the  shore  inland 
from  a  former  station  for  a  distance  of  some  miles. 

In  considering  the  uprising  and  downsinking  of  beaches,  it 
need  not  be  supposed  that  gi'eat  differences  in  the  movement 
of  large  areas  of  the  earth's  surface  are  involved  in  these 
diverse  residts.  It  seems  likely,  indeed  we  may  say  almost 
certain,  that  the  interior  parts  of  the  continents  are  generally 


EFFECT  OF  BEACHES  IX  THE  FOKMATION  OF  H.USUOKS.    KiT 

moving  upward,  while  tlie  sea  floors  are  geuerally  rnoviug 
downward,  in  those  great  wrinkling  processes  of  the  earth's 
crust  which  developed  the  arches  of  the  land  and  the  Imsins  of 
the  sea.  In  this  movement,  which  the  reader  may  for  conven- 
ience represent  to  himself  by  holding  a  pencil  in  the  middle  of 
its  length  and  in  a  sloping  position,  it  is  evident  that  we  may 
regard  the  section  from  the  interior  of  the  land  out  to  the  ])f)t- 
tom  of  the  sea  as  a  bar  or  lever,  which  has  a  fulcrum  point  rep- 
resented, in  the  case  of  the  pencil,  by  the  point  at  which  it  is 
held  between  the  fingers.  Now,  if  it  happens,  as  it  prol^ibly 
does  in  most  cases,  that  the  fulcrum  point  is  near  the  shore, 
we  easily  perceive  that  the  land  may  rise  and  the  sea  floor  sink 
without  necessarily  de}iressing  or  elevating  the  l)each.  If,  on 
the  other  hand,  the  fulcrum  point  is  to  the  landward  of  the 
shore,  the  motion  will  carry  the  beach  below  the  plane  of  the 
sea;  while,  if  the  rotating  point  be  under  the  sea,  the  beach 
will  be  gradually  elevated.  In  this  way  we  may  account  for 
the  very  numerous  changes  in  the  position  of  beaches  without 
having  to  suppose  that  the  land  changes  the  general  nature  of 
its  movement. 

Effect  of  Beaches  in  the  Formation  of  Hahboks. — This 
is  a  matter  at  once  of  scientific  interest  and  of  economic  impor- 
tance. There  are  two  ways  in  which  the  growth  of  a  sand  beach 
may  lead  to  the  formation  of  shelters  for  ships.  AYliere  a  sand- 
barrier  reef  forms  offshore,  it  often  happens  that  one  end  of  the 
strip  does  not  lie  against  any  promontory,  but  ends  in  the  open 
water.  Instances  of  this  sort  may  be  noted  at  many  points  along 
the  Atlantic  coast  of  the  United  (States.  Although  the  sea  be- 
hind such  spits  of  sand  is  commonly  not  very  deep,  the  shelter 
which  they  afford  is  often  of  much  value  tt)  the  smaller  vessels, 
such  as  are  engaged  in  the  coasting  ti-ade.  ^Vliere  such  a  sand 
beach  is  extended  by  the  action  of  marine  currents,  especially 
where  it  projects  into  a  bay,  its  extremity  is  apt  to  be  turned  in 
its  growth  by  the  action  of  other  currents  until  it  assumes  the 
form  of  a  hook,  sui-li  as  may  be  noted  near  Proviucetown,  Mass.; 
at  Cape  Pogue  on  Martha's  Vineyard;  and  at  many  other  points 
along  the  shores  to  the  southward.  Another  group  of  sand-bar 
harljorages  owes  its  oiigin  to  the  inlets  or  breaches  which  are 
formed  where  the  waters  of  a  lagoon,  overfilled  by  the  rivers, 
break  out  into  the  sea.  Good  instances  of  this  nature  abound 
along  the  Atlantic  coast  south  of  Cape  Hatteras.     These  passages 


168  BEACHES  AND  TIDAL  MARSHES. 

from  the  open  ocean  to  the  sheltered  expanses  of  the  lagoons  or 
bays  are  generally  shallow.  In  almost  all  cases  they  are  mnch 
obstructed  by  extensive  sand  bars  both  on  the  ontside  and  inside 
of  the  opening,  —  shallows  formed  by  the  tidal  currents,  which 
obtain  considerable  energy  as  they  move  in  and  out  of  the  nar- 
row chaimel.  As  a  class,  sand-bar  harbors  are,  because  of  their 
shallow  nature,  of  less  value  than  are  those  which  are  formed  in 
other  ways;  but  in  many  regions,  as  along  the  southern  coast  of 
the  United  States,  they  are  about  the  only  shelters  for  ships. 

SuMM.uu'. — "We  have  now  considered  the  most  important  phe- 
nomena of  beaches,  and  the  share  which  these  structures  have  in 
preserving  the  land  from  the  assaults  of  the  sea.  It  would  be  pos- 
sil)le  to  extend  indefinitely  an  account  of  the  facts  of  the  physical 
nati;re  which  these  structures  exhibit.  Such  details,  however, 
would  best  be  left  to  the  unaided  inquiry  of  the  student  who 
undertakes  the  study  of  particular  parts  of  the  shore.  Such  a 
person  will  do  weU  to  extend  his  inquiries  along  two  lines, — the 
one  leading  to  an  investigation  concerning  the  effect  of  winds 
from  different  du*ections  in  altei'ing  the  details  of  sand  beaches ; 
and  the  other,  to  the  development  of  the  various  s^jecies  of 
animals  and  plants  along  both  the  rocky  and  the  sandj'  shores. 
Inquiries  of  the  kind  above  advised  may,  if  properly  dii-ected, 
prove  of  gi'eat  service  not  only  to  the  original  observer,  but  to 
the  science  which  he  is  pursuing.  Well  known  as  are  the  coast 
lines  in  a  superficial  way,  no  portion  of  them  has  yet  been  so 
studied  as  to  complete  om-  knowledge  concerning  the  featm'es 
which  they  exhibit. 

It  will  be  well  for  the  reader  to  understand  that  the  foregoing 
account  of  beach  phenomena  deals  only  with  the  simpler  results 
of  the  complicated  forces  which  take  effect  along  the  lines  where 
the  waters  come  in  contact  with  the  land.  Many  of  the  more 
important  jiroblems  which  are  presented  in  this  most  interesting 
field  of  inquiry  are  not  touched  upon  in  this  brief  essay.  Some 
of  them,  indeed  (as,  for  instance,  the  details  of  wave  action),  have 
necessarily  been  avoided,  for  the  reason  that  their  adecjuate  dis- 
cussion demands  a  treatment  by  means  of  the  higher  mathemat- 
ics. It  may,  however,  be  hoped  that  enough  lias  been  set  forth, 
though  in  mere  outline,  to  guide  the  student  on  the  way  to  investi- 
gations which  he  may  independently  pursue. 


THE  NORTHERN  APPALACHIANS. 


By  Bailey  Willis. 


ENUMERATION   OF   TOPOCiRAPHIC   FEATUKES. 

Usually  a  moiiutam  range  is  iiiavk(Ml  hy  a  central  crest,  but 
the  Appalaoliian  ranges  are  cbaracteri/,('(l  by  a  central  zone,  the 
surface  of  which  is  lower  than  the  ranges  on  either  side.  Tiiis 
zone  is  a  very  complex  valley,  or  series  of  valleys,  and  is  known 
l)y  different  names  in  different  sections  of  its  length  of  a  thousand 
miles.  In  its  entirety  it  will  here  be  designated  the  "Greater 
Ai)palachian  Valley,"  or  the  "  Greater  Valley,"  and  its  parts  will 
be  referred  to  by  their  local  names.  In  eastern  New  Yoi'k  the- 
Greater  Valley  lies  between  the  Catskills  and  the  Green  Moun- 
tains of  Vermont,  and  its  southward  extension  is  the  Wallkill 
Valley  and  the  Panlinskill  in  New  Jersey.  In  Pennsylvania  it 
includes  the  Lebanon,  Lancaster,  and  Cumberland  valleys;  in 
Maryland,  the  Hagerstown  Valley ;  in  Virginia,  the  Shenan- 
doah; and  throughout  Pennsylvania,  Maryland,  and  Vii-ginia, 
the  western  portion  is  occupied  by  the  Alleghany  ridges.  Still 
farther  south  it  is  the  valley  of  East  Tennessee,  which,  dividing 
at  Lookout  Mountain,  extends  into  Alabama  and  Georgia. 

Two  principal  ranges  Ijound  the  Greater  AiJpahu-hian  ^'al- 
ley, — one  on  the  southeast,  the  other  on  the  northwest;  the 
former  being  generally  known  as  the  Blue  Kidge,  the  latter  as 
the  Alleghany  Front.  They  extend  in  two  nearly  i>arallel  lines 
about  75  miles  apart. 

The  Blue  Ridge  is  a  mountain  nnige  of  jirevailingly  gentle 
slopes,  rising  to  rounded  spurs  and  knobs.  It  is  everywhere 
soil-covered,  and  clothed  in  forests  or  cultivated  fii^lds.  It  is 
nowhere  naked  or  barren.  In  tliose  sections  where  wealtli 
creates  summer  homes,  driveways  of  easy  gra(l(>  swing  around 
the  broad  mountain  shoulders,  which  are  dotteil  with  villas  and 
sjiread  with  green  lawns.     Even   in  the  more  remote  districts, 


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ITl'  THE    XOETHEIJX    APPALACHIAN'S. 

fabius  and  eonifit'lds  nestle  among  the  mountain's  arms,  and 
cattle  find  pasturage  on  the  summits.  In  New  Jersey  the  Blue 
Ridge  is  represented  by  the  highlands  above  Morristown;  in 
Pennsylvania  it  is  called  South  Mountain,  and  reaches  an  eleva- 
tion of  2,000  feet  above  the  sea,  or  1,000  to  1,500  feet  above  the 
adjaeent  Cumbei'land  Valley.  Between  the  Susquehanna  and 
Potomac  the  range  lessens  in  l>ulk  and  height  to  narrow  ridges 
but  1,300  feet  above  the  sea.  The  Potomac,  whose  channel  at 
TTarpers  Ferry  is  at  an  elevation  of  .'>00  feet,  is  overlooked  by 
the  historic  eminenciv  of  Maryland  and  Loudon  heights,  which 
are  but  800  feet  higher  than  the  river.  Southward  through 
Virginia,  however,  the  ridge  becomes  broader  and  higher:  30 
miles  from  the  Potomac  the  altitude  is  2,000  feet;  17  miles 
farther  is  Mount  Marshall,  3,150  feet;  11  miles  beyond  is  Marys 
Rock,  3,000  feet ;  and  Stony  Man  and  Hawks  Bill,  4  miles  and  7 
miles  V''si>i'<'tiv('ly  from  Marys  Rock,  and  opposite  Luray,  are 
4,031  and  4,0()()  feet  aliove  the  sea.  These  are  the  highest  sum- 
mits of  the  Blue  Ridge  north  of  North  Carolina,  and  it  is  10  to 
10  miles  across  at  this  point.  In  the  section  between  the  Poto- 
mac and  Mount  Marshall  there  are  three  deep  gaps, — Snickers, 
Ashby,  and  Manassas  gaps, — cut  down  to  levels  of  about  1,000 
feet.  Manassas  Gap,  farthest  from  the  Potomac,  is  about  50 
feet  deeper  than  the  other  two ;  and  waters  of  the  Potomac,  the 
Rappahannock,  and  the  Shenandoah  rise  in  a  small  plain  east  of 
the  gap.  hi  the  section  south  of  Mount  Marshall  and  extending 
100  miles  to  the  James  there  are  numerous  gajts  at  an  altitude 
of  about  2,300  feet. 

The  western  wall  of  the  Appalachian  trough,  the  AUeghanj' 
Front,  is  characterized  in  its  typical  development  by  a  bold 
southeastward-facing  escarpment  and  a  gentle  northwe.<5tward 
slope.  It  is  the  edge  of  the  Alleghany  Plateau.  Its  northern 
end  touclics  tlie  Hudson  River,  and  is  called  the  Catskill  Moun- 
tains. Thence  it  stretcln^s  southwestward  with  a  general  eleva- 
tion of  2,000  feet;  l)Ut  in  northeastern  l?ennsylvaiiia  the  Front 
is  lost  among  the  ridges  which  form  the  rim  of  the  anthracite 
coal  basins.  Tlie  plateau  is  characteristically  developt'd,  how- 
ever, west  of  "Wyoming  and  Nittany  valleys,  and  the  Alleghany 
Front  is  equally  well  marked.  In  this  section  it  is  climbed  by 
the  Pennsylvania  Railroad  in  the  Horseshoe  Bend  between 
Altoona  (l,"lS()  feet)  and  Oresson  (2,020  feet).  The  Front  crosses 
Maryland  between  ('umberland  and  Frostburg;  Dans  ^Mountain, 


TOPOGRAPHIC  FEATUUES.  173 

2,100  feet  abov'e  the  sea,  being  a  eoiispiciious  point.  South  of 
the  Potomac,  it  rises  in  the  Pinnacle  to  3,007  feet,  in  Pigeon 
Roost  to  3,400  feet,  and  in  Roaring  Plains  to  4,400  feet.  Little 
High  Knolj,  20  miles  from  the  Potomac,  is  a  corner,  4,200  feet 
above  the  level  of  the  sea,  in  tlie  boundary  between  Virginia  and 
West  Vii-ginia.  Thence  southwestward  the  Alleghany  Front 
declines  in  elevation,  and  becomes  less  sharply  marked.  The 
Chesapeake  and  Ohio  Railroad  pierces  it  in  a  tunnel  2,100  feet 
above  the  sea  in  passing  from  the  head  waters  of  the  James 
River  to  the  vallej*  of  the  Greenbrier  River.  New  River,  flow- 
ing northwestward,  enters  the  plateau  in  a  canyon  1,500  feet 
deep,  the  general  elevation  of  the  crest  being  more  than  3,000 
feet.  In  the  Big  Black  Mountains  of  Virginia  and  Kentucky  the 
FrOnt  again  attains  heights  of  4,000  feet ;  but  the  summit  is  lower 
in  Tennessee,  and  at  Cumberland  Gap  it  is  but  1,G00  feet. 

Many  streams  cross  the  Alleghany  Front.  Rising  in  the 
plateau,  they  all,  with  the  one  conspicuous  exception  of  New 
River,  flow  southeastwai'd,  and  emerge  from  deep  canyons  into 
minor  valleys  of  the  Great  Valley.  It  will  be  seen  later  that  in 
its  apparently  peculiar  northwest  course  New  River  pursues  the 
more  natural  direction  of  flow,  and  that  the  Delaware,  Susque- 
hanna, Potomac,  James,  and  Roanoke  rivers  reverse  the  <!Ourses 
they  might,  in  the  light  of  the  ancient  history  of  the  province, 
be  expected  to  take. 

As  compared  with  the  Blue  Ridge,  the  scenery  of  the  Alle- 
ghany Front  is  rugged,  yes,  savage.  The  eastern  face  is  steep, 
lofty,  and  often  crowned  with  a  precipice  of  sandstone.  The 
canyons,  a  thousand  feet  deep  or  more  from  the  plateau  to  the 
rivers,  are  narrow,  and  the  profiles  of  the  opposing  walls  are  as 
bold  as  the  eastern  escarpment. 

Between  the  opposite  ranges  of  the  Blue  Ridge  and  Alle» 
ghany  Front  stretches  the  Greater  Appalachian  Valley.  Its  sur- 
face has  a  general  slope,  which  is  interrupted  by  depressions  and 
heights.  The  depressions  are  channels  cut  by  the  streams  in 
intaglio  (that  is,  sunk  below  the  general  surface)  10  feet  to  200 
feet  deep.  The  heights  are  long,  narrow  ridges,  which  remain 
in  bas-relief  (that  is,  stand  out  above  the  general  surface)  upon 
the  plain,  rising  000  to  SOO  feet  above  it.  They  are  ranged  in 
lines,  frequently  parallel  among  themselves  and  to  the  Blue 
Ridge  or  Alleghany  Front.  Through  Pennsylvania  they  sweep 
in  a  majestic  curve,  which  is  followed  by  all  the  ridges  from 


174  THE   JJOKTHEltX    .U>PALACHUNS. 

Kittatinny  Mountain  to  the  Alleghany  Front,  and  which  bends 
down  into  Virginia  as  far  as  New  River. 

A  strip  along  the  southeastern  side  of  the  Greater  Valley  is 
distinguished  from  the  northwestern  portion  by  the  general  al)- 
sence  of  ridges  above  the  prevailing  plain.  The  ridgeless  strip  is 
known  as  the  Appalachian  Valley,  the  Great  Valley,  and  locally 
simply  as  the  Valley.  Its  surface  rises  from  a  least  elevation  of 
500  feet  above  the  sea,  in  Pennsylvania,  to  its  gi-eatest  altitude, 
1,700  feet,  in  southern  Virginia.  Thenc*;  southward  it  gradually 
declines. 

Northwest  of  the  Valley,  dividing  the  Greater  Appalachian 
Valley,  iiins  a  ridge  called  Kittatinny  (or  Blue)  Mountain,  north 
of  the  Susquehanna  and  between  the  Sustiuehanna  and  James 
rivers  more  commonly  called  North  Mountain.  In  Virginia  part 
of  the  range  is  named  Little  North  Mountain,  and  a  higher  one 
immediately  northwest  is  North  Mountain.  Although  divided 
by  many  gaps  as  deep  as  the  Valley  level,  and  varying  in  height 
from  200  to  1,500  feet,  this  ridge  is  a  practically  continuous  fea- 
ture throughout  a  distance  of  400  miles.  Its  crest  is  often  a 
rocky  ledge  less  than  50  feet  across,  yet  it  maintains  a  imiform 
elevation  over  long  stretches. 

Northwest  from  Kittatinny  Mountain  the  Greater  Valley  is 
di^^ded  by  the  many  parallel  Alleghany  ridges  which  succeed 
one  another  to  the  Front  as  wave  lies  beyond  wave  on  the  sea. 
They  are  generally  narrow-crested,  steep,  and  long.  Hidden 
among  them  is  Kishicoquillis  Valley,  a  fertile  plain  25  miles 
long  and  from  1  to  5  miles  wide,  completely  encircled  by  moun- 
tain walls.  Beyond  them,  in  the  sunset  shadow  of  the  Alle- 
ghany Front,  are  Wyoming  and  Nittany  valleys.  The  former 
is  slightly  crescent-shaped,  55  miles  long  and  (5  miles  wide,  and 
js  smoothly  floored  by  deep  alluvial  soil.  It  is  the  Northern 
Anthracite  Basin.  Nittany  Valley  presents  a  less  even  plain, 
the  surface  being  deeply  channeled  by  many  streams ;  but  the 
fertile,  rolling  valley  is  charmingly  diversified  in  its  aspects, 
and  contrasts  beautifully  with  the  escarpment  of  the  Alleghany 
Plateau.  Its  length  is  60  miles,  but  the  southern  arm,  Mor- 
risons and  Fi-iends  coves,  extends  the  feature  50  miles  farther. 
The  width  varies  from  2  to  10  miles,  and  there  are  several  diver- 
gent coves. 

In  Virginia  the  Alleghany  ridges  are  of  a  broader,  less  linear 
type.     They  are  frequently  oval,  in  horizontal  and  vertical  sec- 


TOPOGKAPHIC  FEATURES.  175 

tiou,  both  with  comparatively  smooth  and  gentle  slopes.  The 
valleys  between  tlie  ranges  contain  still  broader  bnt  lower  I'idges, 
among  which  the  head  waters  of  the  Potomac  and  James  rivers 
flow  in  deep,  narrow  gorges.  The  soils  are  thin,  and  the  dis- 
trict is  less  closely  settled  than  the  corresponding  section  of 
Pennsylvania. 

Throughout  Pennsylvania  the  Alleghany  ridges  are  from  1,500 
to  1,800  feet  above  the  sea,  but,  like  the  level  of  the  Valley,  the 
Blue  Ridge,  aiid  the  Alleghany  Front,  they  rise  toward  the  south. 
In  Virginia  many  of  the  ridges  exceed  3,000  feet  in  altitude ;  and 
Elliots  Knob,  20  miles  west  of  Staunton,  has  an  elevation  of 
4,473  feet. 

Ordinarily  a  great  vallej^  is  the  home  of  a  great  river,  which 
flows  the  length  of  the  valley,  gathering  the  waters  from  the  en- 
vironing mountains.  The  Mississippi  is  an  example;  and  in  the 
Southern  Appalachian  ranges  the  Holston  and  Tennessee  rivers 
above  Chattanooga  illustrate  this  relation  of  an  extensive  valley 
which  holds  a  single  river  system.  But  in  the  Northern  Appa- 
lachian ranges  there  are  several  river  systems,  and  their  main 
streams  traverse  the  ranges  in  channels  which  are  in  a  measure 
independent  of  the  ridges.  The  Delaware,  the  Susquehanna,  the 
Potomac,  the  James,  and  the  Roanoke,  all  cross  the  heights. 
New  River  also  cuts  across,  though  in  the  opi)<)sitc  direction. 
Even  the  tributai'ies  are  not  confined  liy  the  ridges.  Following 
down  some  stream,  we  see  the  valley  extending  indefinitely,  an 
easy  path  for  the  loitering  waters.  The  mountains  rise  on  either 
hand.  Suddenly  the  river  turns  ofi'  at  right  angles,  and,  dash- 
ing through  a  narrow  gap  in  the  forbidding  ridge  on  one  side 
or  the  other,  emerges  into  another  valley  parallel  to  its  former 
course.  We  shall  see  that  the  transverse  rivers  are  older  than 
the  existing  ranges,  and  that  they  developed  their  courses  on  a 
broad  plain. 

The  rivers  of  the  Northern  App;ilachi;ins  flow  either  to  the 
Atlantic  or  to  the  Ohio  River.  The  divide  between  these  groups 
of  streams  is  winding  and"  often  inconspicuous,  having  no  defi- 
nite rehition  to  the  principal  heights.  The  Delawar(\  Susque- 
hanna, and  Potomac  rise  west  of  the  Alleghany  Fi'ont,  which 
they  cross,  and,  continuing  eastward,  traverse  the  Alleghany 
i-idges  and  the  Blue  Ridge  to  reach  the  Atlantic.  From  among 
the  Alleghany  ridges  of  Virginia,  the  James  and  Roanoke  flow 
through  the  Blue  Ridge  eastward.     New  River,  on  the  contrary, 


176  THE   XOKTHERX   APP-VLACHIAXS. 

has  its  source  east  of  the  Blue  Ridge  in  North  (^aroliua,  and 
runs  northwest  across  tlie  Bhie  Ridge,  the  Alleghany  ridges,  and 
the  Alleghany  Front,  to  the  Ohio.  Thus  the  main  divide  passes 
diagonally  across  the  Appalachian  ranges  from  a  position  north- 
west of  the  Alleghany  Front  in  Pennsylvania  to  one  east  of  the 
Blue  Ridge  in  North  Carolina.  AVithiu  the  Greater  Valley, 
between  the  Blue  Ridge  and  the  Alleghany  Front,  the  divides 
between  minor  streams  are  intricate ;  but,  again,  they  are  pecul- 
iar in  being  distinct  from  the  valley  ridges  which  they  serve  to 
connect,  but  do  not  follow. 

DESCRIPTION   OF   THE   TOPOGRAPHIC    FEATfRES. 

The  marked  characteristic  of  views  in  the  Appalachian 
ranges  is  the  level  line  in  which  the  even  ridge  tops  appear  in 
silhouette  against  the  sky.  In  landscapes,  as  in  architecture, 
sky  hues  are  tj'pical.  The  severe  outline  of  a  Greek  temple  is  a 
form  distinct  from  the  gi-aceful  spires  of  a  Gothic  cathedral. 
Not  less  widely  do  the  even  profiles  of  the  Appalachians  differ 
from  the  serrate  sky  lines  of  the  Rocky  Mountains. 

From  the  deei:)ly  cut  channel  of  a  stream  in  the  broader 
stretches  of  the  Appalachian  Valley  we  may  ascend  to  a  hilltop 
of  the  general  level.  We  climb  a  slope  of  soil,  wooded  or  culti- 
vated, and  advance  upon  the  level  summit  of  the  knoll.  It  is 
not  a  commanding  height,  and  yet  in  the  absence  of  woods  we 
may  survey  a  broad  landscape.  There  are  many  even-topped, 
rounded  hills :  they  join  one  auothei',  forming  a  gently  rolling 
surface,  in  which  the  streams  are  more  or  less  deeply  sunk  in 
intaglio.  Were  the  trench-like  valleys  filled  to  the  uniform  ele- 
vation of  the  hilltops,  the  surface  would  be  a  plain. 

Looking  northwest  or  southeast,  we  see,  limiting  this  cai'ved 
surface,  a  ridge  which  reaches  far  to  the  I'ight  and  left.  Its 
crest  meets  the  sky  in  an  even  line,  which  is  broken  here  and 
there  by  gaps.  Some  gaps  are  slight  V's,  which  scarcely  inter- 
rupt the  otherwise  even  line.  Other  gaps  are  cut  down  to  water 
level,  and  are  occupied  by  streams  passing  through  the  ridge. 

This  ■s'iew  is  across  the  trend  of  the  ridges,  across  the  gi-ain 
of  the  country.  Turning  to  look  in  the  direction  of  the  trend, 
northeast  or  southwest,  we  may  see  rising  from  the  plain  a  row 
of  knobs,  one  behind  another,  each  fai-ther  one  higher,  to  one 
which  reaches  the  altitude  of  the  level  ridge  tops.  It  is  the  end 
of  a  ridge  which  extends  away  for  many  miles. 


TOPOGRAPHIC  FEATURES.  177 

Thus  the  relief  of  the  Appahichiau  laudscape  has  three  classes 
of  features:  namely,  the  river  ohauuels  with  their  associated 
level  bottoms;  the  upland  or  general  level  of  the  valley,  which 
is  more  or  less  cut  into  I'ounded  hills  of  nearly  equal  elevation ; 
and  the  ridges,  which  also  in  a  general  way  rise  to  a  uniform 
altitude.     Let  us  consider  these  features  more  in  detail. 

It  is  the  habit  of  rivers  to  do  one  of  two  things :  they  either 
dash  swiftly  down  a  rocky  course,  actively  cutting  the  channel 
and  carrying  whatever  sediment  they  receive;  or  they  linger 
between  alluvial  banks,  here  and  thci'e  rippling  over  a  gravel 
bar.  Thus  loitering,  tlicy  drop  their  burden  of  sand  and  mud, 
leaving  it  till  a  freshet  gives  them  energy  to  lift  and  sweep  it 
farther.  Appalachian  streains  leap  and  loiter  alternately.  Usu- 
ally the  quiet  reaches  extend  where  the  waters  wind  about  in  the 
valleys  trending  northeast  or  southwest,  and  the  cascades  are 
found  where  they  traverse  a  ridge  descending  to  a  parallel  val- 
ley. But  when  a  small  stream  joins  one  much  larger,  there  is 
often  a  rapid  or  waterfall  in  the  smaller  of  the  two  near  its 
mouth. 

Occasionally  in  the  large  rivers  a  swift  current  running  in 
and  out  among  rocky  islets  is  margined  by  alluvial  plains.  Near 
Harrisburg,  the  Susquehanna,  which  is  there  broad  and  shallow, 
shows  this  association  of  a  stream  at  work  upon  rock  bottom, 
between  banks  of  gravel  and  sand  which  it  formerly  deposited. 
The  difference  between  the  banks  and  the  channel  shows  that 
the  condition  of  the  river  has  changed. 

With  a  given  current  and  volume,  a  river  can  transport  a 
certain  amount  of  gravel,  sand,  and  mud.  If  it  receives  no  more 
than  it  can  carry,  it  cuts  its  bed;  but  if  it  is  overloaded,  it  de- 
posits some  of  the  sediment.  In  that  case,  if  at  some  subsequent 
time  the  river  should  gain  in  volume  or  velocity,  or  receive  less 
load  from  above,  it  would  go  to  work  to  remove  the  beds  of 
gravel  or  sand  it  had  left  behind. 

The  Susquehanna  near  Harrisburg  Avas  formerly  overloaded, 
and  spread  alluvial  formations  broadly.  Either  because  it  flows 
more  swiftly  or  is  less  loaded  from  its  upper  courses,  it  has  now 
removed  the  sediments  down  to  the  rock.  Other  rivers  also 
show  this  character. 

The  depth  of  the  sunken  channels  cut  by  the  streams  in  the 
general  valley  level  varies  with  the  size  of  the  streams  from  r)0 
to  600  feet.     The  great  rivers  have  cut  deepest,  the  smaller 


178  THE   NOKTHEltX    APPALACHUNS. 

streams  less  deeply,  the  brooks  least;  but  all  streams  flow  most 
of  their  courses  in  uarrow  gorges  with  limited  bottom  lauds. 

These  channels  are  so  intimately  related  to  the  streams,  that 
there  can  be  no  doubt  of  the  truth  of  one  of  two  propositions: 
either  the  streams  took  up  their  present  courses  because  they 
found  them  to  be  the  lines  of  least  altitude,  or  the  streams  flow- 
ing in  these  coiu'ses  have  cut  out  these  lowest  lines.  In  the 
guUey  by  the  roadside  or  on  the  hillside,  in  a  heavy  rain,  you 
may  catch  the  rivulets  at  work.  The  shoAver  over,  you  may 
study  the  forms  they  have  carved.  Down  the  guUej',  dowu  the 
brook,  the  creek,  and  the  tril)utary  to  the  gi-eat  river,  you  can 
trace  the  features  of  the  same  class,  though  of  constautly  in- 
creasing magnitude,  and,  noting  the  burden  of  mud  which  the 
waters  bear,  you  may  realize  that  rivers  do  not  tiud  their  valleys : 
they  make  them. 

The  general  level,  with  which  the  dei>th  of  the  river  chan- 
nels has  been  compared,  is  not  a  uniform  feature  of  the  great 
valley  between  the  Blue  Ridge  and  the  Alleghany  Front.  There 
are  two  classes  of  districts  in  which  it  is  wanting.  Near  the 
larger  streams  it  is  usually  worn  away,  or  so  divided  into  many 
low  hills  that  it  cannot  be  recognized.  On  the  other  hand, 
among  the  higher  ridges,  where  they  are  closely  ranged,  the 
broad  plain  was  not  developed. 

The  plain  is  well  preserved  in  the  Lebanon,  Lancaster,  and 
Cumberland  valleys  of  eastern  Pennsylvania,  and  in  their  south- 
ern continuation,  the  Shenandoah  of  Virginia.  It  is  also  to  be 
seen  high  above  the  present  levels  of  the  streams  in  the  Nittauy 
Valley  of  central  Pennsylvania,  and  in  Kishicoquillis,  which  lies  J, 
in  the  heart  of  the  ranges.  These  valleys  are  all  of  limestone, 
with  some  areas  of  shale  (or  limy  nuid  rock)  in  the  larger  ones. 

But  the  plain  is  not  clearly  evident  in  northern  Pennsylvania 
in  the  anthracite  basins,  nor  in  the  central  part  of  the  State 
along  the  Juniata,  nor  in  West  Virginia  on  the  head  waters  of 
the  Potomac  and  James  rivers.  In  these  districts,  where  hills 
rise  above  the  rivers,  yet  do  not  attain  the  altitude  of  the  high 
ridges,  they  are  nevertheless  of  such  height,  and  so  bold  in  their 
outlines,  that  they  do  not  immediately  suggest  the  ancient  plain 
out  of  which  they  have  been  carved. 

The  high  ridges  next  demand  description.  We  have  seen 
that  in  the  side  view  these  ridges  present  a  horizontal  crest 
interrupted  by  gaps.     With  a  nearly  uniform  elevation  they  ex- 


\ 


TOPOGKAPHIC   FK4TURES.  179 

tend  for  iiiauy  miles,  l)Ut  at  intervals  of  from  cue  to  five  miles 
tljey  are  notched  to  a  depth  of  a  hundred  feet  or  more  below  the 
crest;  and  at  longer  intervals  the  notch  is  cut  down  to  the  base 
of  the  ridge,  and  is  occupied  by  a  stream.  In  the  end  view  the 
section  across  one  of  these  ridges  resembles  a  right-angled  tri- 
angle laid  on  its  longest  edge, — on  the  hypoteiuise.  The  apex 
of  the  right  angle,  then,  represents  the  crest  of  the  ridge;  and 
the  sides  of  the  right  angle  are  the  slopes  of  the  ridge.  The 
cross  section  may,  however,  have  various  forms.  One  slope 
may  be  much  steeper  than  the  othei-.  The  steeper,  being  ]>er- 
haps  precipitous  near  the  sunnuit,  departs  from  the  straight 
lines  of  tlie  triangle  and  descends  in  a  curve,  gi'adually  becom- 
ing less  steep ;  the  gentler  slojie,  approaching  the  horizontal, 
extends  uniformly  to  some  distance.  This  foi-ms  the  unsym- 
metrical  ridge,  of  which  the  Alleghany  Front,  with  its  bold  east- 
ern face  and  gentle  westward  slope,  is  the  extreme  type.  In 
other  cases  the  two  opposed  slopes  are  more  nearly  equal,  and 
the  cross  section  of  the  ridge  may  apjjroaeh  symmetry  or  be 
quite  symmetrical.  In  the  symmetrical  ridge  both  slopes  are 
steep,  l)eing  nearly  foity-ftve  degnn-s  lu'ar  the  sunnuit. 

These  sharji-crested  ridges,  called  iiiohocUiki}  ridi/cs,  run  in 
long  Unes,  straight  or  curving,  often  for  many  scores  of  miles. 
They  may  simply  die  out,  but  freqiieutly  they  pursue  a  shai-ply 
zigzag  course.  Then  the  ridge  rises  to  a  ciilminating  point, 
higher  than  the  extended  crest;  and  from  this  point  another 
ridge,  which  is  really  but  a  continuation  of  the  first,  returns  at 
an  acute  angle  with  the  former's  course.  The  ridge  and  its 
opposite  section,  or  continuation,  are  related  in  position  as  are 
the  sides  of  a  canoe,  and  the  high  peak  occupies  the  i)Osition  of 
the  elevated  prow.  After  a  course  of  a  few  miles,  tlie  second 
section  turns  again,  but  less  sharply  and  without  a  liighcr  peak, 
into  a  third  section,  which  extends  parallel  with  the  first  section. 
At  the  end  of  the  third  section,  where  it  passes  into  a  fourth, 
there  is  again  a  higher  peak, — a  canoe  prow, — and  the  angle  of 
the  zigzag  is  sharp.  Valleys  which  lie  between  the  first  and 
second  sections,  or  between  the  third  and  fourth,  leading  up  to 
and  ending  in  tlie  pi'ow  of  the  canoe,  are  called  (■a)ioc  rallcifn. 
Tlie  intermediate  valleys,  lying  in  tlH>  position  lietween  the  sec- 
ond and  third  sections,  have  no  familiar  name;  but  they  are  aii- 
ticl'mal  rrt//r//.s,  ])vesently  to  l>e  exidained,  while  the  canoe  valleys 
are  more  accurately  described  by  the  term  si/ncliiidl  rallnis. 


180 


THE   NORTHERN   APPALACHIANS. 


Occasionally  the  canoe  valley  is  simple,  and  closed  at  both 
ends,  while  tho  drainajre  escapes  through  one  or  more  gaps  in 
the  side.  Sometimes  such  a  canoe  occurs  as  a  long,  narrow,  and 
shallow  hollow  in  the  crest  of  a  mountain  many  hundred  feet 
above  the  general  valley  level.  The  feature  is  then  called  a 
si/ticlitHiI  mountain. 

The  "Wyoming  Valley  is  an  example,  on  a  large  scale,  of  a 
simple  canoe  valley.  The  anthracite  basins  are  complex  canoe 
valleys,  and  the  zigzag  ridges  by  which  they  are  shut  in  are 
beautiful  examples  of  their  kind  (p.  183). 

These  forms  are  the  prevailing  ones  in  Pennsylvania  and 
Virginia.  In  both  these  States  and  in  West  Virginia  there  is 
also  another  type  of  ridge,  which  is  oval  in  cross  section  and  in 
longitudinal  section.  An  example  of  this  type  may  be  found  in 
Great  North  Mountain,  which  rises  from  the  Valley  northwest 
of  Winchester,  and  extends  30  miles  southwestward,  declining 
to  the  North  Fork  of  the  Shenandojih  River.  Rock  Enon  and 
Capon  Springs  lie  on  its  northwestern  flank.  This  moxantain 
reaches  an  altitude  of  2,700  feet  in  its  nortlieni  section,  1,700  feet 
above  the  general  level  of  the  Valley.  In  tlie  same  locality  it  is 
3  miles  wide  at  the  base,  and  bears  a  broad,  rounded  summit. 
When  seen  in  a  view  in  which  it  presents  its  northern  end,  it  re- 
sembles an  arch.    When  viewed  in  a  northwesterly  direction,  its 


Syiii'liim!  Fold,  with  Central Cauoe-sliaped       Anticlinal  Fold,  with  lliiiii-eiftar-shaped 
Valley.  Mountain. 

profile  is  hemi-cigar  sliape.  Tlie  mountain  is  indeed  an  arch  of 
sandstone,  an  anticline  which  has  to  some  extent  been  denuded 
of  the  strata  that  formerly  covered  it. 

In  the  central  section  of  the  mountain,  which  is  crossed  by 
the  road  from  Middletown  to  Capon  Springs,  the  sandstone  auti- 


TOPOaUAPHIt!  FEATURES.  181 

('line  is  itself  cut  through,  and  the  t-rags  that  overhang  the  road 
on  both  flanks  of  the  mountain  are  only  the  piers  on  which  rested 
the  arch.  It  spanned  the  valley  of  Paddys  Run,  that  now  lies 
in  the  back  of  tlic  mountain. 

Mountains  of  this  oval  type,  anticlinal  mountains,  are  some- 
times isolated  from  all  other  elevations  by  surrounding  valleys. 
In  other  instances  they  lie  en  echelon,  connected  by  a  transverse 
divide  much  lower  than  their  summits;  or,  again,  two  of  them 
may  coalesce  at  one  end,  forming  a  higher,  broader  summit  than 
either  possessed  alone. 

The  canoe  valley  or  synclinal  valley  may,  as  has  already  Ijeen 
stated,  form  the  summit  of  a  long,  narrow  mountain,  whicli  is 
then  called  a  synclinal  mountain.  The  arch  mountain  or  anti- 
clinal mountain  may,  conversely,  not  only  include  a  small  anti- 
clinal valley  in  its  crest,  as  Paddys  Run  Valley  lies  in  Great 
North  Mountain,  l)ut  the  height  of  the  mountain  may  be  replaced 
by  the  hollow  of  the  anticlinal  valley.  This  occurs  through  the 
gradual  expansion  of  the  valh^y  from  the  crest  of  the  arch  toward 
the  sides  and  toward  the  ends,  so  that  th(*  lowest  pai'ts  of  tlie 
long,  narrow  dome  alone  reinain.  These  then  stand  as  mountain 
walls  inclosing  the  valley,  from  which  there  may  be  but  one  gate- 
way leading  out. 

Such  an  anticlinal  valley  is  Kishicoquillis,  in  Mifflin  Coimty, 
Pennsylvania.  Stone  Mountain  on  the  northwest,  and  Jacks 
Mountain  on  the  southeast,  completely  isolate  it,  except  for 
Logans  Gap  in  Jacks  Mountain,  near  Lewiston, — a  pi(!turesque 
gorge  through  which  Kishicoquillis  Creek  dashes.  Passing 
through  this  ravine  into  the  valley,  the  observer  finds  all  the 
characteristics  of  the  Great  Valley  reproduced.  The  stream 
flows  in  a  channel  wliich  is  cut  deeply  into  the  general  siirface. 
Ascending  to  what  appears  from  below  to  be  a  hilltop,  it  is 
found  to  be  only  the  general  level  of  the  valley  floor,  which  rep- 
resents a  former  plain.  The  eucomi)assing  ridges  are  level- 
crested.  Toward  the  southwest  they  converge  to  tlie  apex  of  an 
acute  angle.  Across  the  nortlieastern  end  of  the  valley  they  are 
connected  by  the  zigzag  summits  of  Bi;ffalo  Mountain,  which  re- 
semble the  environing  ridges  of  the  antliracite  basins. 

The  anthracite  basins  arc  canoe  valleys,  but  they  lie  high  up 
above  the  channel  of  the  Susquelianna,  which  receives  the  creeks 
that  drain  them.  Tliey  are  therefore  canoe-rallei/  mountains  or 
synclinal  mountains.    Their  topogra[)hic  character  is  apparent  in 


1S2  THE   NORTHERN   APPALACHIANS. 

thf  aocoinpauj'iug  reliof  map  of  part  of  eastern  Peimsylvauia. 
Keferriiig  to  the  oxtrciiie  northeast  corner,  we  see  Nescopeek 
Mountain  extending  southwest  to  Catawissa  Mountain.  Their 
junction  is  the  western  prow  of  a  canoe  valley  which  a  few  miles 
east  contains  the  Northern  Middle  Anthracite  Basins. 

Cata^Wssa  Mountain  jiasses  in  a  gentle  arch  into  Little  Moun- 
tain, which  forms  with  Line  Mountain  a  second  canoe;  that  is 
to  say,  the  bed  of  hard  sandstone  forming  Little  Mountain  and 
Line  Mountain  is  continuous,  like  the  l)ottom  of  a  canoe,  beneath 
the  space  between  them.  Within  this  trough  lies  a  second, 
which  is  narrower  and  shallower,  being  represented  by  Big  and 
Mahanoy  mountains;  and  within  lie  the  coal  beds  of  the  Shamo- 
kin  Anthracite  Basin. 

]\Iahantango  and  Berry  mountains,  Peters  and  Second  moun- 
tains, form  tlie  outer  rims  of  two  convergent  canoes.  Coal  and 
Lick  mouutiiins,  Stony  and  Sharp  mountains,  are  paired  as  the 
inner  trouglis,  within  which  lie  the  coal-bearing  measures.  East- 
wai-d  from  Tremont  these  two  basins  become  one,  which  extends 
beyond  Pottsville  to  Mauch  Chunk. 

The  preservation  of  the  stores  of  coal  contained  within  these 
basins  is  due  to  their  environing  ridges.  The  soft  strata  of  the 
coal  measures  had  been  worn  down  to  the  level  of  the  Lebanon 
Valley,  and  a  very  large  proportion  of  the  coal  had  been  swept 
away  to  the  sea ;  but  these  walls  of  hard  sandstone  withstood  the 
effect  of  erosion,  and  maintained  the  coal-bearing  mountains. 

The  simple  monoclinal  ridge  which  has  been  def^icribed  is  the 
typical  but  not  the  more  common  form  of  the  Appalachian 
ranges.  They  become  complex  by  association  of  parallel  ridges. 
Thus  on  the  inner  slopes  of  Jacks  and  Stone  mountains,  about 
Kishicoquillis  Valley,  there  is  a  very  marked  bench  or  terrace, 
which  api^ears  as  a  broad  step  in  the  mountain  slope.  In  other 
localities,  wlien  the  outer  edge  of  such  a  terrace  is  higher  than 
its  surface  neai'ei-  the  mountain,  there  are  narrow  ravines  sepa- 
rating tlie  tci'riice  edge  as  a  low  ridge  more  or  less  distinct  from 
tlie  mountain  itself.  The  rivulets  which  gather  in  these  ravines 
occur  oppos(Ml  in  pairs,  like  opposite  loaves  o)i  a  stem,  and  their 
united  waters  flow  at  right  angles  to  the  trend  of  the  main  ridge 
through  gorges  in  the  lower  ridge.  Elsewhere,  again,  although 
ci;t  through  by  many  streams  rising  on  the  main  divide,  the  sub- 
ordinate ridge  may  stand  at  a  level  equal  with  the  continuous 
crest,  and  it  then  appears  as  a  distinct  monoclinal  ridge.    On  the 


if  Map  of  Wosteiu  Portion  of  tlip  Antliiacitc  Basins,  IViiiisylvania.  showing  Canoe  Valleys  and  Mountains  and 

the  Course  of  the  Susijuchanua  across  them,  18a 


I 


184  THE   NOKTHEUN    APPALACHIANS. 

south  side  of  the  authracite  basins  ther«>  are  three  such  crests, 
which  are  nearly  parallel,  and  are  called  First,  .Second,  and  Third 
mountains;  and  there  is  ;dso  Fourth  Mountain,  locally  so  called, 
hut  it  is  in  fact  tlie  continuation  of  Third  Mountain  on  the  north- 
ern side  of  a  canoe  valley. 

In  order  that  we  may  understand  why  these  I'idires  exist,  why 
they  vary  in  form,  and  why  they  jjursue  such  curious  zigzag 
courses,  we  must  observe  the  rocks  of  which  they  are  composed. 
In  the  crests  of  nearly  all  Appalachian  ridges  occur  quartz  rocks 
of  one  variety  or  another.  The  rock  may  be  a  conglomerate  of 
white  pebbles,  or  a  sandstone  of  coarse  or  fine  grains,  or  a  mass- 
ive rock  called  quartzite,  breaking  into  sharp  fragments;  but 
quartz  is  the  predominating  mineral.  Of  all  common  minerals, 
quartz  is  the  hardest  and  least  sohible :  therefore  the  quartz 
rocks  longest  resist  the  action  of  the  atmosphere  in  wearing  and 
dissolving  them.  Lime,  on  the  other  hand,  is  dissolved  with  rela- 
tive rapidity:  therefore  lime  rocks,  such  as  marble,  limestone, 
and  limy  mud  rocks,  decay  quickly  in  a  moist  climate  like  that 
of  the  Appalachians;  the  lime  being  leached  out,  and  red  clay 
remaining. 

These  two  classes  of  rocks,  quartz  rocks  and  lime  rocks,  form 
the  Appalachian  region  between  the  Blue  Ridge  and  the  Alle- 
ghany Front.  There  are  many  varieties,  differing  in  composition, 
texture,  and  color ;  but  they  all  fall  into  the  two  great  classes  of 
the  quartz  rocks  and  the  lime  rocks, — the  relatively  insoluble 
and  the  more  soluble.  The  soluble  lime  rocks  occur  in  the  val- 
leys and  lower  slopes  of  the  ridges;  the  insoluble  quartz  rocks 
form  the  ridge  crests. 

The  quartz  rocks  extend  as  beds  of  conglomerate,  sandstone, 
or  quartzite  between  the  much  thicker  beds  of  lime  rocks.  These 
beds  vary  in  thickness  from  a  few  inches  to  hundreds  of  feet, 
l)ut  a  single  stratum  of  solid  quartz  rock  more  than  iJOO  feet  thick 
is  unusual.  They  extend  downward  from  the  surface  at  differ- 
ent inclinations  in  ditt'erent  districts.  In  the  Alleghany  Front 
they  lie  almost  flat.  Their  edges  make  the  eastern  slope  of  the 
mountain,  and  the  uppermost  one  forms  the  surface  of  the  plateau 
descending  gently  westward.  On  the  other  hand,  in  Kittatinny 
Mountain,  near  Harrisburg,  the  beds  stand  vertical. 

The  form  of  the  ei'oss  section  of  any  ridge  depends  upon  the 
inclination  of  the  beds  of  which  it  is  composed.  Where  the 
strata  are  gently  inclined,  the  height  approaches  more  or  less 


INDEPENDENCE   OK   S'lKEAMS   AND    VALLEYS.  1H5 

nearly  to  the  ehavaeter  of  a  table  inouiitaiu.  In  the  steeper  slope 
the  edges  of  the  beds  are  exposed.  As  the  soft  beds  wear  away, 
the  liarder  beds,  behig  uiiderniiued,  break  oft"  in  Ijloeks,  and  a 
liold  front  remains.  Where  the  base  material  aeeunmlates,  the 
roek  face  is  masked,  and  cliffs  are  visil)le  only  towai-<l  tlie  sum- 
niit.  Where  the  strata,  on  the  other  liand,  are  st(>ep]y  inclined, 
tlie  edge  of  the  hardest  bed  makes  the  crest  of  the  mountain, 
and  more  or  less  symmetrical  slopes  are  woi-n  from  the  adjacent 
beds. 

INDEPENDENCE  OF  GREAT  STREAMS  AND  GREAT  VALLEYS. 

Two  rivers,  rising  in  the  Alleghany  Plateau  far  west  of  the 
Alleghany  Front,  and  joining  in  the  heart  of  the  valley  ridges  of 
Pennsylvania,  form  the  8ns(iu('lKuina.  Their  courses  to  their 
junction  lie  across  many  mountains;  and  the  lower  course  con- 
tinues in  the  same  manner  across  mountains,  even  though  an 
easier  route  over  j^lains  was  near  at  hand.  This  is  well  illus- 
trated in  the  channel  of  the  Susquehanna  a))Ove  Hai-risl)urg,  as 
shown  in  the  map,  pp.  170,  171. 

The  head  waters  of  the  Potomac  li(^  in  the  plateau  west  of 
the  Alleghany  Front.  Large  tributaries  running  northeastward 
in  the  valley  join  it;  and  the  principal  one  of  these,  the  Slicn- 
andoali,  is  the  largest  river  nortii  of  Tennessee  flowing  in  the 
direction  of  the  length  of  the  A]>i>ala('hian  Valley.  But  all  tliese 
waters  assume  in  the  Potomac  a  soutlieasterly  cliannel,  wliii'h  is 
cut  across  the  hard  beds  of  the  valley  ridges. 

New  River,  which  gathers  its  waters  in  North  Carolina,  does 
not  follow  the  line  of  easy  descent  northeastward  along  the  Great 
Valley  to  the  Potomac  or  Susquehanna.  It  chooses  instead  a 
difficult  way  to  the  Ohio  River  across  the  Greater  Valley  and  tlie 
Plateau. 

These  are  examples  of  the;  general  fact  that  the  streams  of 
the  Appalachian  ranges  are  not  controlled  liy  the  mountains. 
The  ridges  i)ursue  their  courses,  and  the  streams  passing  across 
the  ridges  pursue  independent  courses.  The  discordance  is  one 
of  the  most  marked  features  of  the  topography,  and  it  gives  rise 
to  many  picturesqiie  water  gaps.  As  we  shall  see  farther  on,  it 
is  due  to  the  fact  that  the  transverse  river  channels  are  older 
than  the  valley  ridges. 

Within  the  Valley  the  brooks  and   creeks   have  arranged 


18G 


THE   NOKTHERN    APPALACHUNS. 


themselves  usually  in  systems  of  pairs.     Flowing  southwest,  a 
Itrook  meets  its  fellow  running  northeast,  and  together  they  turn 

In  the  valley  be- 


southeast  or  northwest  to  traverse  a  riilgt 


Types  of  Drainage  resulting  from  Ailjustment  to  Beds  of  Hard  and  Soft  Rouk. 

In  tlio  northwest  comer  of  tbc  map  tUe  streams  flow  diversely  over  rocks  which  lie  in  horizontal 
bede.  On  the  head  waters  of  BUiestone  River  and  Wolf  Creeli  the  branches  arc  adjnsted  to 
tilted  hard  and  soft  beds,  fomiinp  an  example  of  "  trelliscd  "  dniinase.  lietwccu  WoK  and 
Hunting  Camp  creeks  is  an  anticlinal  arch.  liiu'ke  Garden,  and  the  systems  ot  streams  de- 
tine  its  position.  Walker  ("r<'ek  and  its  branches  also  flow  across  tilted  beds,  but.  as  ihoy  are 
more  homogeneous  than  tlinsc  ali>ii!.-  the  heads  of  Wolf  Creek,  the  streams  are  less  system- 
atically adUnsted. 


HOW    SCULPTURED.  187 

yoiid  the  ridf^e  they  ave  joiued  l)y  a  pair  siiiiilav  to  their  own 
coui'ses  before  their  union.  Beyond  a  second  ridge  or  a  third, 
the  growing  creek  may  for  a  time  flow  northeast  or  southwest, 
but  it  will  presently  pass  oiit  by  another  water  gap.  Ultimately 
it  falls  into  one  of  the  great  transverse  rivers.  This  arrange- 
ment of  parallel  brooks,  which  swell  the  volume  of  a  creek  gen- 
erally flowing  at  right  angles  to  their  courses,  resembles  a  vine 
from  whose  central  stem  branches  are  trained  on  a  trellis.  It  is 
sometimes  called  the  trdlis  or  (jrapcvine  sij><tc'm. 

Although  most  conspicuously  developed  in  the  Appalachians, 
this  ti'ellis  system  of  drainage  is  common  in  regions  wdiere  lieds 
of  hard  rock  lie  steeply  inclined  to  the  general  surface.  The 
parallel  branches  of  the  system  are  controlled  by  the  parallel 
ridges  between  each  two  pairs.  Thus  it  ap})eai-s  that  the  liai-d 
rocks  have  to  this  extent  influenced  the  arrangement  of  the 
streams. 


HOW  THE   APPALACHIAN   UPLIFT  HAS  BEEN   SCULPTURED. 

We  have  observed  that  the  rivers  flow  in  channels,  which, 
like  the  gullies  they  resemble,  have  been  cut  by  swift-rimning 
waters.  We  have  noticed  also  that  waters  running  less  swiftly 
deposit  mud,  building  flood  plains  or  bottom  lands.  These  two 
processes  are  as  old  as  rivers  and  the  force  of  gravity.  In  the 
course  of  ages  they  will  remove  mountains  and  spread  plains. 
Let  us  ti'ace  their  work. 

Streams  which  carry  sediment  cut  like  a  saw.  Like  a  circu- 
lar saw,  they  file  continuously  into  the  mass  opposed  to  them. 
This  is  the  mass  of  land  above  sea  level,  and  they  saw  their  chan- 
nels from  their  mouths  backward  into  it.  Thus  every  stream 
tends  to  cut  its  channel  throughout  its  entire  course  down  to  the 
level  of  its  mouth.  But  in  this  tendency  it  is  checked  when  its 
fall  becomes  so  gentle  that  it  deposits  sediment.  Then  it  can 
no  longer  cut  downwai'd,  but  it  begins  to  carve  sidewis(>. 

By  depositing  sand  or  mud,  a  stream  builds  bars,  from  which 
it  swings  off  against  its  bank.  Undermining  this,  it  is  deflected 
toward  the  other  bank,  which  it  may  strike  and  undercut  in 
turn.  Thus,  when  a  river  has  filed  its  channel  downward  to  a 
gentle  sloi)e  on  which  it  deposits  sediment,  it  then  begins  to 
wind  sidewise,  and  with  ever-increasing  crookedness  widens  its 
valley.     The  rock  and  soil  which  it  cuts  away  are  swept  on  in 


188  THE  NORTHERN   APPALACHIANS. 

flood  tide,  aud  are  left  by  the  subsiding  waters,  t'ormiug  a  flood 
plain.     The  Mississippi  is  thus  at  work. 

Vallej's  are  widened  by  otlier  processes  wliich  aid  the  streams. 
By  heat  aud  cold,  moisture  aud  frost,  vegetation  and  solutiou, 
rocks  are  shattered  and  they  decay.  The  talus  and  soil  remain- 
ing sink  down  to  a  slope  more  gentle  than  that  of  canyon  walls 
such  as  streams  cut  in  hard  rocks.  The  loosened  material  creejis 
down  the  hillside.  Gullies  grow  backward  into  it,  and  develop 
many  arras,  through  which  the  gathered  waters  of  a  storm  sweep 
the  soil  to  the  lowlands.  Every  space  betweeu  the  streams  is 
attacked  sooner  or  later,  and  the  higher  parts  of  the  surface  are 
graded  down.  The  tendency  is  in  time  to  I'eduee  the  land  to  a 
gently  sloping  plain,  which  extends  from  the  sea  to  the  head 
waters  of  the  rivers.     Such  a  plain  is  called  a  base-level. 

The  development  of  a  base-level  over  a  broad  area  I'equires  a 
long  time,  and  does  not  progress  equally.  There  are  many  con- 
ditions that  affect  the  rate  at  which  the  surface  wastes,  but  that 
wliich  most  concerns  us  here  is  the  relative  softness  or  hardness 
of  the  rocks.  In  the  moist  Appalachian  climate,  other  things 
being  equal,  a  soft  or  soluble  rock,  like  calcareous  shale  or  lime- 
stone, wastes  away  much  faster  than  harder  or  insoluble  quartz 
rock,  and  therefore  beds  of  the  harder  rock  may  long  remain  in 
relief  above  a  base-level  extended  over  the  areas  of  softer  rock. 

Let  us  again  look  over  the  Appalachian  landscape.  It  has 
certainlj'  been  sculptured  by  flowing  water,  to  which  the  deep 
channels  of  the  streams  are  due.  Could  some  Titan  fiU  these 
channels  level  with  the  hilltops  of  the  Greater  Valley,  he  would 
restore  a  plain  which  would  extend  over  the  area  of  soft  rocks 
between  the  ridges  of  hard  rocks.  This  is  the  character  of  a 
base-level,  aud  we  cannot  doubt  that  such  a  jilain  was  developed 
by  the  sti-eams  before  they  began  to  cut  their  present  cliannels. 
Let  us  call  this  plain,  which  is  well  preserved  in  the  Shenandoah 
Valley,  the  Shenandoah  base-level. 

Above  this  base-lev(4  the  valley  ridges  rise  200  to  1,800  feet. 
Neighboring  ridges  are  usually  of  nearly  the  same  height,  and 
their  crests  are  often  level  lines,  but  slightly  broken.  Such  lines 
are  elements  of  a  plain,  and,  with  our  eyes  opened  l)y  sugges- 
tion, we  may  see  that  they  do  represent  one.  But  it  is  only 
through  the  extensive  landscape  studies  of  Professor  Davis  and 
of  Messrs.  Hayes  and  Campbell  that  we  are  assured  that  the 
ridge  tops  were  once  even  witli  the  surface  of  a  base-level  which 


HOW   SCULPTURED.  189 

was  much  older  than  the  Shenandoah  Plain.  Let  us  call  this 
older  plain  the  Kittatinuy  base-level,  because  it  is  well  preserved 
in  the  even  crest  of  the  long  mountain  of  that  name. 

To  restore  the  Kittatinny  Plain  ^ve  must  fill  in  with  many 
cubic  miles  of  rock  all  the  Greater  Valley  between  the  Blue 
Ridge  and  the  Alleghany  Front,  at  least  level  with  the  ridge 
crests.  This  done,  however,  we  should  have  a  broad,  dome- 
shaped  elevation  4,000  feet  above  the  sea  in  southwest  Virginia, 
and  sloping  gently  to  the  Atlantic  and  the  Mississippi. 

Geologists  date  this  Kittatinny  Plain  as  of  the  so-called  Civ- 
taceous  period  of  the  earth's  history.  If  we  should  compare  all 
the  ages  since  the  beginning  of  rocks  and  oceans  on  the  earth 
with  all  the  years  since  luiman  existence  began,  the  Cretaceous 
period  would  correspond,  perhaps,  with  the  Roman  occupation 
of  Britain.  Thus  vaguely  we  may  indicate  that  the  Cretaceous 
belongs  to  the  later  periods  of  the  earth's  development.  But 
the  tiine  which  has  since  elapsed  has  been  sufficient  for  the 
growth  of  the  Appalachian  ui)lift,  and  the  erosion  of  its  valleys 
and  ranges.  From  what  we  have  seen  in  the  landscape,  we  may 
reconstruct  an  outline  of  this  growth. 

A  base-level  is  the  lowest  slope  to  which  rivers  can  reduce  a 
laud  area.  With  one  margin  it  touches  the  sea,  from  which  it 
rises  imperceptibly.  Unless  it  be  very  old  and  very  completely 
planed,  hills  may  survive  at  some  distance  inland,  or  over  areas 
of  the  hardest  rocks.  Such  a  surface,  which  is  almost,  but  not 
quite,  a  base-level,  is  called  a  peneplain.  On  such  a  surface  the 
rivers  meander  in  wide  oxbows  throughout  their  ^■allevs.  There 
are  no  marked  divides.  Under  these  conditions,  the  i-hanni'ls  of 
rivers  are  unstable  features,  as  is  that  of  the  Mississippi  or  the 
Missouri;  and,  the  fall  of  a  river  or  system  of  rivers  being  very 
slight,  a  moderatt^  tilting  of  the  land  surface  may  suffice  to 
change  the  courses  of  streams  very  greatly,  or  even  cause  them 
to  flow  in  a  reversed  direction.  The  Kittatinny  peneplain  was 
very  extensive,  and  almost  complett^ly  planed.  The  only  heights 
in  the  Appalachian  region  wei'c  hills  which  are  now  the  jiioun- 
tain  summits  of  western  North  Carolina,  i)ut  wei-e  then  at  a 
lower  altitude.  The  land  was  flat,  featureless,  and  vei-y  sliglitly 
elevated  above  the  sea.  The  courses  of  the  streams  had  been 
adjusted  during  the  long  period  of  erosion ;  and  the  five  rivers 
flowing  eastwai'd  had  assunied  that  course  in  consequence  of  a 
tilting  of  the  land  toward  the  Atlantic,  which  caused  them  to 


190  THE  NOETHEKN   .\PPALACHL\XS. 

reverse  their  courses,  which  were  formerly  northwestward. 
New  River  did  not  share  in  this  reversal,  and  remains  to  record 
the  original  slope  from  an  eastern  continent  toward  an  interior 
sea.  From  this  condition  began  the  growth  of  the  i:)resent  Ap- 
palachian Mountains. 

Along  a  zone  corresponding  with  the  present  Great  Valley 
the  earth's  sui-face  rose  unequally  and  very  slowly  to  a  maxi- 
mum height  of  about  1,400  feet  in  central  Virginia.  The  eleva- 
tion grew  very  gradually,  sloping  to  east  and  west,  and  to  the 
Gulf  of  8t.  Lawrence  on  the  north,  as  well  as  to  the  Gulf  of 
Mexico  on  the  south.  Upon  the  surface  of  this  broad  dome  the 
Susquehanna,  Potomac,  James,  Roanoke,  and  New  rivers  mean- 
dered in  i-ourses  closely  coincident  with  those  they  now  possess. 
They  had  assumed  these  courses  on  the  Kittatiuny  base-level, 
where  the  beds  of  hard  and  soft  rock  of  the  Appalachian  ranges 
were  Imried  beneath  the  alluvium  of  their  flood  jilains.  As  the 
base-level  swelled  upward,  the  rivers  descended  to  the  sea  with 
swifter  flow.  They  resumed  the  work  of  cutting  their  channels 
vertically,  as  they  had  done  before  the  Kittatinuy  Plain  was 
base-leveled,  and,  removing  the  mantle  of  a]lu\-ium,  they  discov- 
ei-ed  the  solid  rock  ribbed  with  beds  of  sandstone  and  quartzite. 
Their  com*ses  lay  across  these  beds ;  and,  although  lines  of  easier 
channel  cutting  lay  along  the  outcrops  of  soft  beds,  the  gi-eat 
rivers  could  only  persist  in  their  channels,  which  they  corraded 
as  rapidly  as  the  hard  beds  rose  athwart  their  coui'se.  The 
water  gaps  by  which  these  rivers  pass  across  the  ranges,  such 
as  that  at  Harpers  Ferry,  and  those  on  the  Susquehanna  above 
Harrisburg,  and  that  on  the  Delaware  near  Strou(lsl)urg,  are  the 
result  of  the  rivers'  sawing. 

On  the  Kittatinuy  Plain  many  smaller  streams  flowed  across 
the  ranges ;  and  they  also,  persisting  in  their  courses  during  the 
upheaval,  cut  water  gaps  in  the  hard  beds.  But  they  could  not 
deepen  the  gaps  as  rapidly  as  did  the  great  rivers,  and  the  work 
of  the  smaller  streams  is  now  represented  by  the  notches  in  the 
ridges  high  above  the  Shenandoah  Plain.  No  streams  now  flow 
through  these  little  V's :  they  are  nind  gaps  from  which  a  ri^^l- 
let  descends  on  each  side  of  the  ridge.  Further  explanation  is 
necessary  Ijefore  we  can  understand  how  this  change  has  come 
about,  but  a  discussion  of  a  single  instance  will  make  it  clear. 

The  Potomac  traverses  the  Blue  Ridge  at  Harpers  Ferry. 
South  of  this  water  gap  are  several  wind  gaps,  such  as  Snick- 


HOW   SCULPTURED. 


191 


ers  Gap,  which  mark  the  chauuels  of  aucient  streams,  now 
diverted.  The  Shenandoah  Eiver  enters  the  Potomac  above 
the  water  gap  at  Harpers  Ferry,  flowing  northward  along  the 


^\ 

•>  J) 

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".  // 

''^ 

,  ,.' 

THE 

o.J^ 

•.^A4/en 

KITTATI  HNY 

y^ 

PLAIN 

f(     ■■  ■■  O 

S^ 

y     ./  Q 

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" — ^^ 

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A3i 

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^;^'  ^'' 

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/y 

\f 

Arrangement  of  Streams  nn  the  Kittatinny 
Plain. 


.Uljunted  Streamn  on  the  ShenantloaK 
['lain. 


Methods  and  Kesults  of  Kivor  Piracy. 

western  base  of  the  Bhie  Ridge.  The  streams  which  passed 
through  Snickers  Gap  and  the  other  wind  gaps  ran  above  the 
present  course  of  the  Sheiiaudoiih,  ci'ossing  it  al)ont  at  right 
angles.  The  two  drainage  systems  could  not  exist  at  one  time: 
therefore  it  is  evident  that  the  older  one  has  been  replaced  by 
.the  younger  river, .the  Sheuandoali.  This  diversion  took  place 
by  the  gradual  growth  of  the  Shenaudoali  from  its  mouth  south- 
ward. The  Potomac,  the  large  stream,  cut  its  water  gap  faster 
than  Snickers  Gap  was  cut.  The  Young  Shenandoah  of  the 
Kittatinny  Plain,  a  small  ti-ibutary  of  the  Potomac  where  tlie 
mouth  of  the  present  Shenandoah  is,  acquii-ed  considerable  fall 
as  the  Potomac  deepened  its  gorge,  and  sawed  its  channel  down 
rapidly  in  the  limestone,  which  offered  no  great  resistance.  But 
the  stream  in  Snickers  Gap,  with  perhaps  less  fall  and  not  nuu-h 
greater  volume  than  the  Shenandoah,  had  to  saw  nuich  harder 
rock  in  crossing  the  Blue  Ridge.  Its  channel  remained  high, 
therefore,  as  compared  Avith  that  of  the  Shenandoah.    The  latter, 


19'_*  THE   NOKTHEKN   APPALACHIANS. 

exteudiug  its  head  waters  backward  as  a  tree  puts  out  new  twigs, 
eventually  tapped  the  channel  of  the  other  stream  above  Snick- 
ers Gap.  The  waters  above  the  jwint  of  attack  joined  the  Shen- 
andoah ;  the  section  between  the  point  of  attack  and  Snickers 
Gap  was  reversed  as  the  Shenandoah  rapidly  deepened  the  chan- 
nel of  its  new  conqiTcst ;  and  the  lower  portion  of  the  stream, 
now  called  Bejncrdam  Creek,  having  lost  its  original  head 
waters,  took  its  rise  at  Snickers  Gap.  Thus  the  ancient  stream 
which  once  flowed  through  the  gap  was  divided  into  three  sec- 
tions,— the  diverted,  the  inverted,  and  the  beheaded, — while 
the  Shenandoah,  the  diverter,  was  strengthened. 

By  successive  captures  of  tliis  kind  the  piratical  diverter  has 
grown,  until  it  is  now  the  largest  of  the  rivers  within  the  Val- 
ley; and  its  head  waters  approach  the  channel  of  the  James, 
wliich  it  may  in  time  add  to  its  conquests. 

This  process  of  capture  of  a  small  sti'eam  by  a  larger  one,  or 
of  a  stream  cutting  hard  rock  by  one  making  a  deeper  channel 
in  soft  I'ock,  or  of  a  sluggish  stream  by  one  having  a  rapid  fall, 
takes  on  many  aspects.  It  is  a  phase  of  that  adjustment  by 
which  rivers  tend  to  take  the  easiest  route  to  the  sea. 

Furthermore,  in  consequence  of  this  adjustment,  streams  are 
diverted  frona  areas  of  hard  rock  to  areas  of  soft  rock,  and  the 
hard  rocks  remain  as  divides.  Thus  in  the  case  of  the  Shenan- 
doah all  of  tlu'  formerly  indei)endent  streams  which  crossed  the 
Blue  Ridge  are  now  concentrated  in  the  channel  of  that  one 
river.  The  coml)ined  waters  are  working  rapidly  to  reduce  the 
surface  of  the  Shenandoah  Plain,  while  the  Blue  Ridge  remains 
subject  only  to  the  attacks  of  rain  and  tiny  rills.  Adjustment 
of  streams  not  only  establishes  divides  on  the  hard  rocks,  but 
also  diverts  the  waters  that  are  cutting  across  tlunn. 

The  drainage  system  of  the  Kittatinny  Plain  was  developed 
in  the  alluvium  of  the  base-level.  When  it  discovered  the  hard 
and  soft  rocks  of  the  Ajipalachian  zone,  it  was  out  of  adjust- 
ment, and  the  streams  competed  for  tlunr  courses  after  the 
manner  described.  The  more  powerful  or  more  advantageously 
situated  rivers  held  their  own,  and  conquered  their  neighbors. 
Thus  there  are  in  the  ju-esent  drainage  system  the  older  rivers 
which  occupied  their  jiresent  channels  when  carving  the  Kitta- 
tinny Plain,  and  the  subsequent  streams  wliich  developed  as  the 
upheaved  plain  was  cut  into. 

"When  the  upheaval  was  in  progress  and  while  it  was  young. 


HOW   SCULPTUKED.  lijij 

the  cavviug  was  intaglio,  —  canyons  or  deep  channels  like  those 
of  the  present  landscape  were  sunk  toward  sea-level ;  but  as  the 
streams  became  adjusted  among  themselves  and  to  the  ranges 
of  hard  and  soft  rocks,  and  their  fall  lessened,  they  began  to 
widen  their  valleys.  In  course  of  a  long  time  they  carved  out 
the  Greater  Valley,  leaving  the  ridges  of  hard  rock  in  relief,  to 
record  in  their  level  crests  and  wind  gaps  the  extent  of  the  Kit- 
tatinny  Plain  and  the  direction  of  its  drainage. 

The  arching  of  the  somewhat  corrugated  dome  which  bi'ought 
aljout  the  adjustment  of  the  streams  proljably  went  forwanl 
steadily,  though  gradually.  It  ceased,  and  for  a  relatively  long 
period  the  Appalachian  uplift  remained  about  constant  in  ele- 
vation. The  adjusted  rivers  in  their  lower  courses  constructed 
flood  plains,  which  spread  toward  tlie  head  waters  as  the  vall(>ys 
were  ci;t  more  deeply.  A  base-level  plain  was  extended  througii- 
out  the  valley  from  the  great  rivers  back  to  the  slopes  of  the 
ridges.  It  is  now  rejn-esented  in  the  general  level  which  wa 
liave  called  the  Shenandoah  Plain. 

The  Shenandoah  base-level  is  less  extensive  than  the  Kitta- 
tinny  was.  It  is  limited  to  areas  of  the  soft  rocks.  With  these 
it  is  coextensive,  and  the  period  of  its  development  was  so  long 
that  all  the  areas  of  soft  rocks,  even  to  the  head  waters,  were 
planed;  but  it  was  cut  so  short  that  none  of  the  ridges  of  liai'd 
rock  were  anywhere  leveled. 

The  swelling  of  the  Appalachian  dome  began  again.  It  rose 
200  feet  in  New  Jersey,  600  feet  in  Pennsylvania,  1,700  feet  in 
southern  Virginia,  and  thence  southward  sloped  to  the  CJuU"  of 
Mexico.  Its  vertical  arcs  are  from  the  Mississippi  to  the  Atlantic, 
from  Nova  Scotia  to  the  Gulf.  The  axes  of  gi'eatest  uplift  lie 
along  the  central  valley;  but  their  relations  are  not  simple,  and 
the  study  of  their  details  involves  problems  of  stream  adjust- 
ment which  are  of  deep  interest. 

In  consequence  of  the  renewed  elevation,  the  streams  were 
revived.  Once  more  falling  swiftly,  they  have  sawed  and  are 
sawing  their  channels  down,  and  are  prejiaring  for  the  develoj)- 
ment  of  a  future  base-level. 

In  the  valleys  ]K)werful  rivers  are  planing  soft  rocks.  Along 
the  ridge  crests  weak  rivulets  attack,  but  do  not  much  affect,  the 
masses  of  hard  quartzite :  therefore  the  ridges  are  being  left  in 
even  higher  relief,  —  the  Appalachian  ranges  are  becoming  more 
acute. 


VM  THE   NOETHEKN    APPALACHIAXS. 

GENESIS   OF   THE   APPALACHLVN   T\TE   OF   MOfNTAINS. 

Narrow  valleys  aud  linear  ridges,  arranged  iu  more  or  less 
complex  relations,  are  often  described  as  being  of  the  Appala- 
chian tj-pe ;  not  because  such  ranges  are  uncommon  features  of 
the  earth's  surface,  but  because  nowhere  else  iu  the  world  is  this 
form  of  topography  so  characteristically  aud  extensively  devel- 
oped. Nevertheless  monoclinal  ridges  and  streams  adjusted  to 
longitudinal  and  transverse  valleys,  associated  with  syuchnal 
aud  anticlinal  valleys  or  mountains,  are  found  in  all  moimtain 
systems  except  those  which  are  composed  mainly  of  volcanic  or 
massive  igneous  rocks.  We  may  recall  the  fact  that  the  Appa- 
lachians are  formed  of  beds  of  rock, — of  hard  and  soft  beds 
occurring  in  alternation  and  inclined  at  angles  varying  from  the 
horizontal  to  the  vertical, — and  we  should  not  expect  to  find 
this  type  of  topography  developed  in  masses  of  homogeneous 
granite,  such  as  that  which  constitutes  Pikes  Peak  or  the  south- 
ern part  of  the  Sierra  Nevada. 

Bedded  rocks  are  produced  by  various  agencies, — by  succes- 
sive eruptions  from  volcanoes,  by  winds,  by  flood  waters  of 
rivers  or  from  melting  glaciers,  and  by  deposits  of  sediments 
beneath  lakes  aud  seas;  but  of  the  deposits  thus  formed  only 
those  which  accumulate  beneath  somewhat  extensive  bodies  of 
water  are  sufficiently  regular  in  bedding  to  develop  into  ranges 
of  the  Appalachian  type  when  upheaved;  and  of  such  marine 
formations,  only  those  which  are  so  bent,  during  u]>heaval,  as  to 
present  their  ujiturued  edges  to  erosion,  develop  the  Appalachian 
type  of  topography. 

As  illustrations  of  these  facts  we  may  refer  to  the  foothills  of 
the  Rocky  ^lountains,  where  the  "hog-back  ridges"  are  typical 
forms ;  or  in  Eurojie  to  the  Jura  Mountains  and  other  outlying 
ranges  about  the  Alps,  which  present  very  striking  examples  of 
monoclinal,  synclinal,  and  anticlinal  features. 

Beds  of  sediment  which  are  spread  beneath  the  sea  consist  of 
gravel,  sand,  and  clay,  together  with  lime,  and  many  other  sub- 
stances in  smaller  pi-oportions.  All  of  these  materials  are 
brought  to  the  sea  by  rivers  flowing  from  more  or  less  extensive 
land  areas,  or  are  gnawed  from  the  shoi'es  by  waves  and  carried 
out  to  sea  by  the  undertow.  A  bed  of  sediment  is  spread,  it  is 
Imried  beneath  another  bed  of  similar  or  different  .sediment, 
which  in  turn  is  itself  buried:  and  the  layers  harden  into  rock, 


GENESIS   OF   THE   APPALACHIAN   TYPE.  195 

forming,  of  sancl,  sandstone;  of  clayey  mud,  shale;  and  of  limy 
ooze,  limestone. 

This  process  of  deposition  goes  on  for  ages.  The  materials 
vary  in  character  according  to  conditions  both  on  the  land  and 
in  the  sea.  The  strata  become  perhaps  several  thousand  feet 
thick.  They  sink  somewhat  into  the  earth's  mass;  so  that  the 
sea,  though  receiving  great  volumes  of  land  waste,  remains 
deep.  But  after  ages  of  subsidence,  forces  within  the  earth, 
whose  origin  and  character  are  unknown,  reverse  the  move- 
ment, and  raise  the  sea  bottom  to  form  dry  land.  The  strata 
may  be  simply  upheaved  and  tilted  from  their  original  horizon- 
tal position,  or  they  may  be  compressed  by  a  force  of  inconceiv- 
able power  which  gradually  bends  them  into  corrugations  that 
consist  of  successive  arches  and  troughs. 

This  upheaval  is  the  birth  of  a  range  of  the  Appalachian 
type.  In  a  short  time,  as  the  earth's  ages  are  counted,  streams 
cut  canyons  in  the  newly  exposed  surface;  in  the  process  of 
adjustment  to  hard  and  soft  rocks,  jjiratical  brooks  grow  to  the 
stature  of  rivers  by  the  capture  of  less  favored  streams ;  through 
the  resistance  of  hard  strata,  ridges  develop)  and  become  prom- 
inent; but  in  time  the  surface  is  reduced  to  a  peneplain,  and  the 
rivers,  meandering  broadly  in  their  extensive  flood  plains,  are 
liable  to  great  changes  of  course  in  consequence  of  gentle  tip- 
ping of  the  land.  During  a  subsequent  age  the  subterranean 
forces  may  again  act  to  upheave  the  land ;  the  rivers  are  then 
revived,  and  begin  anew  the  process  of  degradation,  which 
ceases  only  when  the  monotonous  base-level  is  extended  over 
the  land.  The  process  includes  the  development  and  the  wast- 
ing-away  of  a  generation  of  ridges,  and  thus  generation  after 
generation  may  succeed  one  another  as  often  as  the  earth's  sur- 
face rises  higher  than  the  level  of  a  peneplain. 

Such  has  been  the  genesis  and  history  of  the  Appalachian 
ranges. 

During  the  Paleozoic  era,  an  era  long  prior  to  the  develop- 
ment of  the  Kittatinny  Plain,  a  seashore  extended  where  now 
the  Blue  Eidge  rises.  It  was  not  the  Atlantic  coast  of  a  smaller 
North  America.  It  was  the  western  coast  of  Appalachia,  a 
continent  which  lay  between  an  interior  sea  on  the  west  and  the 
Atlantic  on  the  east.  Beneath  the  interior  sea  were  deposited 
sediments,  which  formed  the  beds  of  rock  now  found  in  the 
Appalachian  ranges.     In  the  movements  of  the  earth's  rocky 


i;)l)  THE  NOKTHERN  .\PP.\LACHIANS. 

envelope  the  strata  between  the  Blue  Ridge  and  the  Alleghany 
Front  have  been  bent  and  upturned.  Their  edges  are  now  ex- 
posed throughout  the  Greater  Valley.  But  the  zone  in  which 
the  beds  are  thus  steeply  inclined  extends  from  the  Blue  Ridge 
westward  only  so  far  as  the  Alleghany  Front.  In  the  Front 
itself  and  in  the  plateaus  west  of  it  the  strata  approach  a  hori- 
zontal position.  The  steep  face  of  the  Front,  which  is  turned 
eastward,  presents  to  view  the  edges  of  the  fiat  beds. 

In  enumerating  tlie  ]trincipul  features  of  the  Nortliern  Appa- 
lachian ranges  we  distinguish  three, — the  Blue  Ridge,  the 
Greater  Valley,  and  the  Alleghany  Front.  We  now  see  that 
these  three  divisions  are  genetically  related,  and  owe  their 
characters  to  geographic  conditions  that  no  longer  exist.  The 
Blue  Ridge  is  part  of  the  ancient  continent  of  Appalachia, 
which,  being  composed  of  hard  but  generally  homogeneous 
rocks,  maintains  a  mountain  range  vrliose  forms  are  rounded. 
The  Greater  Valley  corresponds  to  a  zone  along  the  shore  of  the 
ancient  sea,  where  the  littoral  formations  consisted  of  alternat- 
ing beds  of  sandstone,  shale,  and  limestone.  These  beds  have 
been  bent  into  arches  and  troughs,  and  in  process  of  erosion 
their  edges  have  developed  as  linear  valleys  and  ridges.  The 
Alleghany  Front  is  simply  the  edge  of  the  plateau,  the  edge  of 
the  region  of  nearly  flat-bedded  rocks  which  have  been  raised 
withoiit  marked  bending.  The  three  constitute  a  group,  in 
■which  the  Bhie  Ridge  may  be  called  a  rontiiiciital  range;  the 
Greater  Valley,  a  tiltriJ  Utfnral  zone  ,•  and  the  Alleghany  Front, 
which  confronts  the  old  continent  of  Appalachia,  an  ii/land- 
facing  escarpme)it. 

These  names  imply  a  recognition  of  seas  and  shores  that  have 
vanished,  and  which  were  not  fixed  features  even  of  the  earlier 
geographic  conditions.  Shores  are  shifting  lines,  and  migrate 
back  and  forth  over  land  surfaces.  But  the  three  gi'eat  topo- 
graphic divisions  of  the  Appalachians  may  nevertheless  be 
classified  according  to  the  conditions  in  which  they  originated. 
Thus  considered,  the  Appalachian  ranges  are  found  to  be  a 
remarkably  complete  development  of  a  type  whose  homologues 
are  distributed  in  all  continents. 

INFLUENCE   OF  THE   APPALACHIANS   ON   SETTLEJIENT. 

The  Appalachian  ranges  lie  l)etween  zones  of  plateaus.  On 
the  east  and  southeast  are  the  Piedmont  Plateaus,  and  on  the 


INFLUENCE  ON  SETTLEMENT.  197 

west  aud  northwest  are  tlie  Allegliauy  Plateaus.  Beyond  these 
zones  respectively  lie  the  Atlantic  Coastal  Plains,  aud  the  Prairie 
Plains,  bordering  the  Mississippi  Valley. 

The  plains  were  the  homes  of  the  most  populous  Indian 
tribes,  and  they  were  first  settled  by  the  invading  Spanish, 
English,  and  French.  The  ranges  of  the  mountains  separated 
these  peoples,  and  were  a  barrier  to  intercourse  long  after  the 
several  topogra})hic  provinces  had  come  under  one  national 
government,  and  their  inhabitants  had  become  one  nation. 

In  this  connection  it  is  desirable  to  note  certain  characteris- 
tics of  the  Appalachians,  bearing  upon  their  effectiveness  as  a 
barrier.  The  ranges  are  marked  by  great  length.  They  are 
continuous  along  hundreds  of  miles.  Like  a  series  of  gigantic 
walls,  they  lie  athwart  the  path  of  one  Avho  travels  northwest- 
ward. They  are  pierced,  it  is  true,  by  numei'ous  passes, — the 
water  gaps, — but  the  gajss  through  the  successive  ridges  are  not 
opposite  one  another,  and  they  resemble  rather  breaches  choked 
by  debris  than  open  gateways. 

Before  the  days  of  railroads,  or  even  of  graded  highways,  the 
migrating  Indian,  or  white  man,  made  his  way  on  foot,  on  horse- 
back, with  pack  horses,  or  by  canoe.  Uu  the  hunt  and  in  war- 
fare he  went  unencumbered,  and  took  little  note  of  natural 
obstacles.  To  break  through  the  underbrush,  to  climb  among 
fallen  trees  and  rocks,  to  ascend  steep  mountains,  or  to  carry 
the  light  canoe  around  rapids,  was  the  hunter's,  the  wai'rior's, 
accustomed  task.  But  the  family  or  the  tribe,  conveying  house- 
hold goods,  foimd  thickets,  Avindfalls,  steeps,  and  cataracts  most 
serious  impediments  to  their  progress,  and  they  were  controlled 
in  the  direction  of  their  migivitions  to  a  great  extent  by  the  ease 
or  difficulty  of  journeying;  and  this  was  more  especially  the 
case  when  the  best  hunting  gvoiinds  or  best  farming  land  lay 
along  the  easiest  route. 

All  the  natural  conditions  which  govern  the  welfare  of  a 
people  inhal)iting  a  district  depend  more  or  less  upon  the  tojiog- 
raphy.  The  flora,  fauna,  water  sui)iily,  h(>althfuluess,  attrac- 
tiveness, and  accessibility  are  conditioned  by  the  nature  of  tlie 
soils,  the  evenness  or  i-uggedness  of  the  surface,  the  elevation 
above  sea,  and  the  distribution  of  streams.  The  four  great  dis- 
tricts of  the  Appalachians  —  the  Great  Valley,  the  Blue  Ridge, 
the  Alleghany  Ridges,  and  the  Alleghany  Plateaus — differ  in 
all  these  respects. 


198  THE   NOETHEEN   APPALACHLiNS. 

The  Great  Valley  is  by  uatuve  adapted  to  be  the  home  of  a 
dense  poinilatioii.  It  has  harljored  many  peoples,  who  have 
warred  for  its  possession.  It  was  a  natural  route  along  which 
tril)es  wandered  from  tiie  pine  or  hardwood  forests  of  the  North 
to  the  cane-brakes  of  the  South,  or  vice  versa,  and  from  which 
there  was  intermigration  and  commercial  intercourse  with  the 
dwellers  along  the  coast. 

The  study  of  the  distril)ution  of  Indian  languages,  and  of  the 
ancient  village  sites,  shows  that  probably  two  great  waves  of 
migration,  and  perhaps  nioiv,  passed  through  the  Valley  before 
Columbus  landeil.  The  Algonfjuins,  spreading  from  their  homes 
about  the  Lakes  and  the  St.  Lawrence,  pushed  far  to  the  south- 
ward, and,  as  fishermen  and  crop  i-aisers,  made  their  homes 
wherever  fish  were  abundant  or  the  soils  fertile.  Behind  them 
and  at  a  later  period  came  the  warlike  tribes  of  the  Iroquois,  the 
most  progressive  of  the  Indians  of  eastern  North  America.  The 
Iroquois  of  the  Six  Nations  drove  the  Algonquius  westward; 
and  the  Cherokees,  also  a  branch  of  the  Iroquois,  occupied  the 
Appalachians  southward  to  Tennessee  and  Georgia.  There  they 
were  overpowered  bj^  the  Watauga  men  under  John  Sevier,  and 
driven  to  the  Carolina  mountains,  where  a  remnant  of  the  tribe 
still  exists.  The  rising  power  of  the  Six  Nations  was  likewise 
destroyed ;  for  their  home  in  northern  New  York  lay  in  the  path 
of  both  Fi'ench  and  English,  and  they  were  drawn  into  the  wars 
which  foreigners  waged  for  lauds  that  belonged  to  the  Indian. 

The  immigration  of  the  whites  was  directed  by  the  natural 
highways,  and  limited  by  the  mountain  l)arriers.  The  seafar- 
ing Dutch  and  English  found  a  congenial  habitat  aroiind  the 
estuaries  of  the  Coastal  Plains.  Slowly  they  worked  their  way 
westward.  "  Blue  Mountain,"  signifying  the  asi^ect  of  the  range 
from  a  distance,  was  the  name  they  gave  to  the  most  eastern 
ridge;  and  it  became  so  fixed  during  the  decades  which  passed 
before  they  had  a  nearer  acquaintance  with  the  ni(iuntnins,  that 
it  survives  to-day  in  two  distinct  ranges, — the  Blue  Ridge  of 
Virginia,  and  the  Blue  or  Kittatiuny  Mountain  of  Pennsylvania. 

In  eastern  Pennsylvania,  however,  the  noi-thern  end  of  the 
Great  Valley  is  easily  accessible;  and  settlement  spread  into  it 
both  north  and  south  of  the  Susquehanna.  In  Virginia  the  low 
passes  just  south  ot"  the  Potomac  afforded  easier  routes  across 
the  ridge  than  the  water  gnp  of  the  river  itself,  and  they  were 
occupied  liy  roads  along  which  pioneers  jiassed  into  the  Valley. 


INFLUENCE  ON  SETTLEMENT.  19U 

There  Wiuchester  was  lard  out  as  a  towu  iu  1752.  It  does  uot 
appear  that  the  Virginians  spread  beyond  the  head  waters  of  the 
Roanoke  during  the  earlier  immigration,  the  Tennessee  region 
having  been  occupied  from  North  Carolina  by  men  who  crossed 
the  highlands  of  that  State.  The  diversion  of  migration  from 
the  Great  Valley  eastward  followed  the  natural  features.  On 
the  head  waters  of  the  Roanoke  two  ridges  rise  to  a  height  of 
more  than  3,000  feet  aljove  the  sea,  between  the  Blue  Ridge  and 
North  Mountain,  and  they  appear  so  to  close  the  Valley  that  the 
old  maps  show  a  range  definitely  limiting  its  southci-n  extension. 
From  this  supposed  mountain  range,  beyond  which  lay  an 
unknown  land,  pioneers  turned  through  the  low  passes  of  the 
Blue  Ridge  toward  the  Piedmont  Plateaus  of  North  Carolina. 

In  1770  there  was  published  in  London  the  "  American  At- 
las," engraved  by  Jeffreys  from  maps  and  surveys  dating  from 
1770  to  1775.  These  maps  present  an  accurate  picture  of  the 
extent  of  settlement,  so  far  as  it  is  indicated  by  the  gi-owth  of 
roads  into  the  wilderness,  and  the  existence  not  only  of  towns, 
but  of  houses  which  served  as  stopping  places. 

In  New  York  the  valleys  of  the  Hudson  and  the  Mohawk  had 
been  occupied,  forming  a  belt  more  than  200  miles  long  from 
New  York  to  the  farthest  outpost,  which  in  1775  was  "  Rynards, 
the  uppermost  settlement,"  70  miles  in  a  straight  line  beyond 
All>any.  Eastward  roads  were  continuous  with  those  of  New 
England,  and  towns  were  numerous ;  but  west  of  the  Hudson 
and  north  or  south  of  the  Mohawk  the  zone  of  civilization  was 
but  5  to  30  miles  wide.  The  Adirondacks  were  dcscribeil  as  "a 
long  chain  of  snowy  mountains,  .  .  .  not  only  uninhabited,  but 
unknown."  That  part  of  the  Appalachian  Valley  from  Ron- 
dout  to  Port  Jervis  on  the  Delaware,  now  the  line  of  tht^  Delaware 
and  Hudson  Canal,  was  developed  Ijy  an  "  Indian  Road  opened 
in  1756,"  which  extended  to  Easton  and  Reading.  Thus  the 
settlements  were  connected  all  along  the  northern  and  eastern 
sides  of  the  Alleghany  plateaus.  The  plateaus  in  southern  New 
York  and  northern  Pennsylvania  were  the  "  Endless  JNIountains," 
and  included  the  "  Great  Swamp."  The  broad  ))lank  on  the  map 
which  these  names  cover  west  of  the  Delaware  is  expressive  of 
a  terra  incoomta. 

In  Pennsylvania  there  were  houses,  mills,  churches,  and 
towns  scattered  throughout  the  region  east  of  Kittatinny  Moun- 
tain: that  barrier  limit(>d  tlunr  expansion.     Lancaster  was  an 


'JOO  THE  NOKTHEKX   APP.VLACHIANS. 

important  ceuter,  couuected  by  two  roads  with  Philadelphia 
and  Wilmington  on  the  east,  by  three  roads  with  points  in  the 
Lebanon  Valley,  and  by  two  others  with  the  West  and  South,  as 
far  as  those  parts  of  the  country  were  then  known.  West  of 
Kittatinny  Mountain,  however,  was  the  labyrinth  of  the  Alle- 
ghany ridges,  through  which  few,  save  perhaps  a  Leatherstock- 
ing,  could  guide  the  injniigraut.  Roads,  which  no  doubt  followed 
former  Indian  trails,  are  shown  here  and  there  on  the  map ;  but 
it  is  evident,  from  the  manner  in  which  their  courses  appear  to 
traverse  the  most  diflficult  ridges,  that  the  map  maker  worked 
without  accurate  knowledge,  and  the  beautiful  series  of  ranges 
that  is  showu  on  pp.  170, 171,  is  delineated  by  him  as  a  confusion 
of  heights.  The  district  of  the  anthracite  basins  is  marked 
"  St.  Anthony's  Wilderness,"  Imt  the  existence  of  coal  is  noted 
in  several  places. 

Southward  from  Lancaster  the  main  road  ran  through  York, 
by  Williams  Ferry  on  the  Potomac,  to  Winchester ;  and  Win- 
chester "was  connected  with  North  Carolina  by  a  road  extending 
along  the  western  side  of  the  Valley  to  the  gap  of  the  Roanoke 
in  the  Blue  Ridge.  Passing  through  that  gap,  it  was  continued 
to  the  Yadkin  River  in  what  is  now  Stokes  County,  North  Caro- 
lina. This  is  marked  "  The  Great  Road  from  the  Yadkin  River 
through  Virginia  to  Philadelphia,  distant  435  miles."  In  all  the 
fertile  valley,  from  Winchester  south,  there  was  in  1775  biit  one 
place  worthy  to  be  named  on  the  map,  "  Staunton  Courthouse."^ 
Probably  along  this  road  passed  Daniel  Boone  when  his  father 
migrated  from  the  frontier  home  near  Reading  to  another  on  the 
Yadkin,  whence  Boone  set  out  in  17G9  to  explore  the  wilderness 
of  the  head  waters  of  the  Tennessee,  and  to  penetrate  along  the 
route  through  Cumberland  Gap  to  Kentucky.  In  thus  marking 
out  the  "  Wilderness  Road,"  Boone  overcame  the  mountain  bar- 
rier which  had  elsewhere  turned  the  tide  of  English  immigration. 

From  the  explorations  of  La  Salle,  a  hundred  years  l)efore 
Boone's,  France  had  laid  claim  to  the  valley  of  the  Mississippi. 
No  mountains  barred  the  advance  of  the  French  voyageiirs,  who 
sailed  the  Great  Lakes,  and  made  their  way  in  canoes  along  the 
numerous  rivers  and  lakes  of  the  interior.  Moreover,  they 
adai)ted  themselves  readily  to  the  Indian  character  and  life,  and 
thiis  in  the  century  of  skirmishing  which  preceded  the  capture 
of  Quebec  they  luul  over  the  English  the  advantage  of  easy 
access  to  the  interior  and  the  aid  of  Indian  allies. 


INFLUENCE  ON  SETTLEMENT.  201 

The  fharacter  of  the  French  and  ludiau  War  was  iu  large 
measure  due  to  the  separatiou  of  the  aiitagouists  by  the  t>road 
wilderness  of  the  AUeghauy  plateaus.  Whatever  blow  Avas  struck, 
whether  it  was  an  Indian  raid  upon  the  English,  or  Braddock's 
expedition  against  Fort  Duquesne,  was  a  l)low  at  arm's  length. 
Even  if  successful,  it  could  not  be  followed  to  decisive  victory. 
In  this  harassing  but  inconclusive  warfare  the  English  were 
within,  the  French  outside,  the  mountain  wall.  Like  men  be- 
sieged within  a  fort,  the  English  were  on  tlie  defensive,  while 
the  French  could  never  muster  force  enough  to  break  in,  even 
through  such  natural  In-eaches  as  the  valley  of  Lake  Cham])]ain 
and  the  Hudson. 

Thus  the  Ajipalachian  ranges,  by  confining  early  English 
immigration,  gave  those  colonies  sti'ength,  and  by  excluding 
organized  attacks  protected  them.  But  toward  the  close  of  the 
eighteenth  century  the  dividing  ranges  sei^arating  the  English 
on  the  east  from  their  countrymen  on  the  west  became  a  source 
of  weakness. 

In  the  years  succeeding  1780  many  thousand  men,  women, 
and  children  ci'ossed  the  Alleghanies  to  Kentucky.  They  went 
by  three  routes,  two  of  which  met  at  Fort  Durpiesiie  (now  Pitts- 
Imrg),  whence  the  journey  was  continued  l)y  l^oat  down  the  ( )liio. 
The  northern  road  from  eastern  Pennsylvania  crossed  the  Sus- 
quehanna at  Harris's  Ferry  (now  Hnri-i8l)urg),  passed  along  the 
Valley  through  Carlisle  to  8hippens))urg,  and  thence  woxuid 
through  the  Alleghany  ridges  past  Bedford.  Ascending  fo  the 
summit  of  the  Alleghany  Front,  the  road  thence  followed  the 
highland  between  the  waters  of  the  Youghiogheny  on  the  south 
and  the  Loyalhanna  on  the  north.  Thus  it  avoided  the  deep 
ravines  which,  clogged  witji  falkm  timber,  rocks,  and  dense 
growth  of  rhododendron,  made  the  plateaus  almost  inqtassable. 
The  second  road  ran  from  Fort  Cumlierland  (now  Cnmberland, 
Maryland)  across  the  Alleghany  plateaus  to  Great  Meadows, 
near  the  present  site  of  Deer  Park,  IMaryland.  Thence  it  turned 
north  to  the  Youghiogheny,  an<l  followed  that  stream  to  the 
Monongaliela  and  to  Pittsburg.  This  was  the  route  cut  out  by 
Washington  and  Braddock  in  1759.  These  were  mountain  roads 
of  the  poorest  description.  AVhere  the  natural  surface  was  fairly 
hard  and  level,  the  track  of  one  wagon  was  the  guide  of  the 
next.  In  swamps  corduroy  made  of  logs  loosely  laid  across  the 
way  formed  an  insecure  bridge.     In  ravines  the  rocky  bed  of 


202  THE  NORTHERN   APPALACHIANS. 

the  Stream  furnished  the  roadway.  On  hillsides  the  narrow 
grade  became  deeply  gullied.  At  seasons  they  became  almost 
impassable,  except  to  the  ready  frouticrsmau,  who  conld  build 
around  or  bridge  over  deep  gullies  or  treacherous  mudholes. 
The  third  route  was  Boone's  "  Wilderness  Trail "  through  Cum- 
berland Gap.  Available  only  for  pack  trains,  not  for  wagons, 
and,  like  tlie  Ohio  route,  open  to  Indian  attack,  it  was  less  used, 
though  even  along  its  rugged  way  many  jiassed  to  join  in  build- 
ing up  the  new  State  in  the  West. 

The  men  of  Kentucky  were  strong,  determined,  and  inde- 
pendent. They  were  separated  from  their  kindred  of  the  eastern 
seaboard  by  diversity  of  interests  as  well  as  by  natural  obstacles. 
Their  prosperity  depended  on  the  commercial  freedom  of  the 
Mississippi  even  more  than  that  of  the  eastern  communities 
depended  on  free  commerce  in  the  Atlantic  ports.  But  the  pol- 
iticians of  the  settled  States  were  inclined  to  treat  lightly  the 
interests  of  the  remote  pioneer  settlements,  and  especially  to 
consider  the  navigation  of  the  Mississippi  as  of  little  importance. 
Hence  from  ITS-t  to  1788,  during  the  negotiations  with  Spain  in 
which  she  claimed  the  right  to  control  the  Mississip2>i,  the 
allegiance  of  Kentucky  to  the  United  States  was  severely 
strained.  Movements  toward  separation  were  considered.  Had 
they  been  carried  out,  the  division  of  the  country  would  have 
been  due  in  large  measure  to  the  broad  wilderness  which  made 
the  communities  of  the  East  strangers  to  those  of  the  West. 
The  Alleghany  plateaus  formed  a  natural  barrier  along  which 
the  States  might  have  di^ndcd. 

During  the  closing  j-ears  of  the  eighteenth  and  the  earlier 
decades  of  the  nineteenth  century,  projects  of  internal  improve- 
ment related  chiefly  to  the  building  of  roads  and  canals  to  over- 
come or  lead  around  the  mountains. 

Pittsl)urg  remained  the  center  of  trade  from  the  East  to  the 
SouthAvest,  but  as  late  as  1811  the  principal  route  for  traffic  was 
through  the  Moliawk  Valley  by  flatboats  and  wagons.  Not 
until  that  year  <lid  Pennsylvania  I'ouse  to  the  importance  of 
building  a  turnpike  from  Harrisburg  to  Pittsburg. 

At  the  present  time  we  traverse  this  distance  in  about  nine 
hours.  Kailroads  liave  penetrated  the  heart  of  the  plateau 
region,  and  beyond  the  railroads  tramways  extend  to  the  most 
remote  recesses.  The  o])ject  of  their  construction  is  to  develop 
the  natiiral  resources  of  the  forests  and  of  the  rockv  strata. 


NIAGARA  FALLS  AXD   THEIR   HISTORY. 


Bv  Ct.  K.  Gilbert. 


The  great  catai-act  i.s  the  embodiment  of 
power.  lu  every  second,  uncea.'^ingly,  seven 
thousand  tons  of  water  leap  from  a  eliif  one 
hundred  and  sixty  feet  higli,  and  the  continu- 
ous lilow  tliey  strike  makes  the  earth  tremble. 

It  is  a  spectacle  of 
great  Ijeauty.  Tlie 
clear,  green,  pouring 
stream,  forced  with 
growing  speed  against 
the  air,  parts  into 
rhythmic  jets  which 
burst  and  spread  till 
all  the  green  is  lost  in 
a  white  cloud  of  spray, 
on  which  the  rainbow 
floats.  Its  charms  are 
the  theme  of  many 
a  gifted  bard  and 
artist,  but  the  fascina- 
tion of  its  ever-varied 
yet  continuous  mo- 
tion, and  the  awe  that 
waxes  rather  than 
wanes  with  familiarity,  are  not  to  be  felt  at  second-hand ;  and  so 
the  world,  in  long  procession,  goes  to  see.  Among  the  multitude 
there  are  some  whose  appreciation  of  its  power  has  a  utilitarian 
phase,  so  that  they  think  most  of  the  mjiiad  wheels  of  industi'y 
its  energy  may  some  day  turn ;  and  there  are  a  few  who  recog- 

(Copyright,  1895,  by  American  Book  Company.) 


Fig.  1. — AmLiieiiu  I'all  iiuiu  bcluu. 


L'04  XIAdAK.V    FALLS    AND    THEU;    IIISTOIIY. 

iiize  it  as  a  gi-eat  natural  engiue,  and  in  its  activity  and  its  sur- 
roundings see  an  impressive  object  lesson  of  geographic  progi-ess. 
Its  aesthetic  and  utilitaiian  aspects  need  no  exi)onnder,  but  its 
geographic  signilioance  is  too  little  appreciated.  This  paper  en- 
deavors to  tell  in  simple  language  some  of  the  lore  of  the  pro- 
fessional geographer  and  geologist,  in  order  that  the  layman 
may  gain  pleasure  not  only  from  the  Iteauty  and  grandeur  of 
the  scene,  but  through  understanding  its  meaning  as  a  part  in 
the  great  drama  of  nature. 

Nature  is  full  of  change.  The  bud  we  saw  yesterday  is  a 
flower  to-day ;  the  leaf  that  was  broad  and  green  in  summer,  in 
autumn  is  shriveled  and  brown ;  the  biish  we  knew  in  childhood 
is  now  a  broad,  spi-eading  tree.  Such  changes  are  easily  seen, 
l)ec-ause  they  fall  ^\ithin  the  span  of  a  man's  life,  and  so  the 
pnucijile  of  perpetual  progress  in  the  organic  world  is  familiar 
to  all.  Progress  in  the  inorganic  world  is  so  slow  that  it  is  less 
easily  seen,  and  there  is  a  widespread  impression  that  the  hills 
are  everlasting  and  unchanging.  This  impression  is  false.  Not 
only  hills,  biit  mountains,  plains,  and  valleys,  are  perpetually 
acted  on  by  heat  and  cold,  sunshine  and  rain,  wind  and  stream, 
and  are  gradually  changed.  Not  only  do  they  now  undergo 
change,  but  by  such  agents  each  feature  was  originally  foiined, 
and  l>y  such  agents  it  will  eventually  l)e  transfoi'med  into  a 
feature  of  dift'ereut  type.  Thus  every  element  of  the  landscape 
has  an  origin  and  a  history.  To  relate  these  is  to  explain  it. 
This  monograph  may  be  regarded  as  an  explanatory  account  of 
Niaa-ara  Falls  and  the  associated  natural  features. 


THE   DK.UXAGE   SYSTEM. 

The  drainage  system  of  the  St.  Lawrence  is  of  exceptional 
character.  In  most  regions  the  freshly  fallen  rain  gathers  into 
I'ills ;  these,  as  they  run,  join  one  with  another,  making  brooks ; 
brooks  are  united  into  rivers ;  and  rivers  flow  to  the  sea.  In  all 
its  journey  from  the  hillside  to  the  sea,  the  water  moves  forward 
Avithout  halt.  This  uninterrupted  journey  is  rendered  possible 
by  a  wonderful  adjustment  of  slopes.  The  channel  of  the  rill 
slopes  toward  the  brook,  the  bed  of  the  brook  sloi)es  toward  the 
river,  and  the  liver  bed  slopes  "toward  the  sea.  Impelled  by 
gravity  to  flow  downhill,  the  water  moves  continually  forward 
from  the  beginning  to  the  end  of  its  journey.     In  the  drainage 


THE   DE.UXAGE   SYSTEM.  205 

district  of  the  St.  Lawrence  there  is  no  such  continuity  of  slope. 
The  district  is  composed  mainly  of  a  gi'oup  of  great  basin-like 
hollows,  i)i  each  of  Avhioh  the  suiface  slopes  toward  some  central 
point,  and  not  toward  the  mouth  of  the  river.  Each  basin  is 
filled  with  water  to  the  level  of  the  lowest  point  of  its  rim,  and 
each  of  the  lakes  thus  formed  is  a  storage  reservoir  i"ecei\ing  a 
group  of  streams  from  the  surrounding  country,  and  pouring  an 
even  discharge  over  its  rim  to  one  of  its  neighbors.  Lakes 
Superior  and  Michigan  discharge  to  Lake  Huron ;  Huron  over- 
flows to  Erie;  and  Erie,  having  thus  received  all  the  outflow  of 
the  upper  and  greater  lakes,  sends  its  suri)lus  through  the  Niag- 
ara to  Ontario.  The  Niagara  Eiver  is  thus,  from  one  point  of 
view,  a  sti'ait  connecting  two  inland  seas ;  from  another  point  of 
view,  it  is  a  part  of  the  St.  Lawi-enee  River, — the  part  connect- 
ing two  great  esiaansions.  Viewed_eithfir--way,  it  d^^pm-ts  so 
jvidely  from  the  ordinary  oi'  normal  UiLer_tha,t4ts-nftffie  i«  almost 
mislea(lijUj8;^- 

In  a  normal  di'ainage  system  the  slope  is  not  everj-^vhere 
equally  steep :  it  is  gentler  in  the  bed  of  the  main  stream  than  in 
the  beds  of  tributaries,  and  it  varies  from  point  to  point  so  that 
the  ciirrent,  esijecially  at  low  water,  shows  an  altei'uation  of 
rapid  and  quiet  reaches.  The  streams  of  the  Laurentian  system 
not  only  exhibit  these  alternations,  but  have  many  cataracts 
where  the  water  cascades  down  a  rocky  stairway  or  leaps  from 
the  brink  of  a  cliii". 

A  normal  river  receives  most  of  its  water  directly  from  rain 
or  melting  snow,  and  varies  with  the  season,  swelling  to  a  flood 
in  time  of  storm  or  at  the  spring  snow  melting,  and  dwindling 
to  relative  insignificance  in  time  of  drought.  The  water  of 
Niagara  comes  only  remotely  from  st<)rm  and  thaw.  The  floods 
of  the  tributaries  are  stored  by  the  lakes,  to  whose  broad  sur- 
faces they  add  but  a  thin  layer.  The  volume  of  Niiagara  dejiends 
onjy  on  the  height  of  Lake  Erie  at  Buffalqj_and  Irom  season  to 
season  this  height  varieslnit  little.  On  rare  occasions  a  westerly 
gale  will  crowd  the  lake  water  toward  its  eastern  end,  and  the 
rivei-  will  grow  large.  On  still  rarer  occasions  a  winter  storm 
^\^ll  so  }iile  up  or  jam  the  lake  ice  at  the  entrance  to  the  river  as 
to  make  a  dam,  and  for  a  day  or  two  the  river  will  lose  most  of 
its  water. 

A  normal  river,  with  its  continuous  current,  rolls  foi'ward  the 
pebbles  loosened  by  its  tributaries  till  they  reach  its  mouth. 


20G 


XIAG.UJA   FALLS   AXD  THEFR   HISTORY. 


The  rains  that  make  its  floods  dislodge  particles  of  soil,  and  wash 
them  into  the  tributaries  in  such  multitude  that  they  discolor 
the  water.  The  pebbles  of  its  bed  and  the  mud  A\-ith  which  it  is 
discolored  are  the  river's  load,  which  it  transports  from  the  face 
of  the  land  to  the  bed  of  the  sea.  The  tributaries  of  Niagara 
carry  their  loads  only  to  the  lakes,  where  the  loads  sink,  and  leave 
the  water  pure.  Thus  Niagara  is  ever  clear.  Sometimes,  when 
storm  waves  lash  the  shores  of  Erie,  a  little  sand  is  washed  to  the 
head  of  the  river,  and  carried  downstream ;  sometimes  a  little 
mud  is  washed  into  the  river  by  the  small  creeks  that  reach  its 
lianks.  Thus  Niagara  is  not  absolutely  devoid  of  load,  but  its 
burden  is  so  minute  that  it  is  hard  to  detect. 


THE   TWO   PLAIN'S. 


From  Lake  Erie  to  Lake  Ontario  the  Niagara  runs  north- 
ward.    The  longer  axes  of  the  lakes  trend  nearly  east  and  west, 

and  the  lakes  lap  past  each 


L  A  E  I         j:  n  I  £ 


Fig. 


-Xiasara  River  ami  Vicinity. 


B  J  '^  Other  for  a  distance  of  forty 
miles,  including  Ijetween  their 
parallel  shores  a  strii)  of  land 
al)out  twenty-five  miles  wide. 
This  strip,  where  the  liver 
crosses  it,  consists  of  two 
plains,  shai'iily  separated  by 
a  cliff  or  est-arpment.  The 
relations  of  the  plains  to  the 
escai-pment  and  to  the  lakes 
are  shown  by  the  map  (Fig.  2) 
and  the  bird's-eye  A-iew  (Fig.  -4).  The  upper  and  broader  plain 
has  a  gently  undidating  smface,  which  does  not  diflfer  greatly  in 
height  from  the  surface  of  Lake  Erie.  Along  the  shore  of  that 
lake  it  rises  in  a  low  ridge,  and  there  is  also  a  gentle  rise  toward 
the  escari>ment.  Its  middle  part  is  di'ained  by  two  .sluggish 
creeks, — the  Tonawanda,  flowing  to  the  river  from  the  east ;  and 
the  Chippewa,  from  the  west.  The  lower  and  narrower  plain 
follows  the  shore  of  Lake  Ontario,  and  rises  gently  thence  to  the 
foot  of  the  escaipment.  Its  ui)per  part  is  of  rolling  contour,  like 
the  upper  plain ;  its  lower  is  remarkably  smooth  and  even,  ha-\-ing 
once  been  the  bed  of  a  lake.  The  escarpment  is  a  steep  slope 
about  two  hundred  feet  high.    Near  the  top  it  is  generally  a  rocky 


THE   TWO    PLAINS.  207 

cliff,  giving  a  sharply  defined  lioundary  to  the  uiipev  plain ;  at  the 
bottom  it  merges  insensibly  with  the  lower  plain. 

These  surface  features  are  definitely  related  not  only  to  the 
peculiarities  of  the  river,  but  to  the  rocky  franiewoi-k  of  the 
country.  The  i'<icks  are  flat  layers  or  strata  I'esting  one  upon 
another,  and  of  neai'ly  uniform  thickness  for  great  distances. 
Nearly  but  not  quite  level,  they  slope  gently  toward  the  south; 
the  descent,  or  dip,  amounting  on  the  average  to  thirty-five  feet 
per  mile.  Their  arrangement  is  illustrated  by  Fig.  3,  which  gives 
a  north-and-south  profile,  with  such  a  section  of  the  fonnatious 

IAK£:  ESCARPMtNT 

£f,ic  Upper  Plain  |  ^^^ 

l^er     Plain         Ontario 


Fl(i.  3.  —  Profile  and  Section  from  Lakp  to  Lako. 
Vertical  scale  greater  than  horizontal.    Base  line  ifprcsents  sea  level. 

as  might  be  seen  if  a  very  deep  trench  were  dug  from  lake  to 
lake.  The  heavy  line  at  the  left,  and  the  Ijelt  below  divided  into 
blocks,  represent  limestones,  rocks  notably  hard  and  strong, 
while  the  intervening  spaces  are  occuisied  chiefly  by  shales, 
which  are  relatively  soft  and  Avcak.  Originally  all  the  forma- 
tions extended  farther  to  the  north,  Init  they  have  been  worn 
away ;  and,  since  the  soft  rocks  were  removed  more  easily  than 
the  hard,  the  edges  of  the  hard  are  left  sonu'wliat  prominent. 
This  association  of  hard- rocks  with  uplands  and  cliffs  is  not  rare, 
but  is  rather  the  rule  in  hilly  and  mountainous  districts.  In  the 
last  preceding  monograph  of  this  series,  Mr.  Willis  describes  the 
plateaus  and  ridges  of  the  Appalachian  district,  showing  how 
frost  and  .^torm  slowly  but  i)ei-sistently  ate  out  the  soft  rocks, 
and  the  rock  waste  was  washed  into  streams,  till  valleys  and 
lowland  jilains  were  made. 

The  higher  of  the  two  limestones  jn-esented  in  the  diagram  is 
called  the  Corniferous  limestone.  It  makes  a  low  ridge  along 
the  north  shore  of  Lake  Erie,  and  dips  beneath  the  lake.  The 
Salina  shales  occupy  the  middle  part  of  the  upper  plain,  and  dip 
V)eneath  the  Cornifei'ous.  The  second  limestone,  called  the 
Niagara  limestone,  constitutes  the  northern  part  of  the  uj^jjer 
plain,  and  the  escarpment  everywhere  marks  its  northern  limit. 
Its  full  thickness  is  about  a  hundred  and  forty  feet,  Init  in  some 
places  it  has  been  greatly  reduced  by  the  wasting  of  its  upper 
surface.     Below  it  is  a  gi-eat  series  of  mud  rocks  or  shales,  a 


208 


XUGAKA   FALLS   AXD   THEIK   HISTOKY. 


thousand  feet  thick,  interrupted  near  the  top  1  ly  a  few  thin  l)eds 
of  Umestone  and  sandstone.  These  shales  occupy  the  lowei- 
part  of  th(>  escarpment  and  the  whole  of  the  lower  plain.  Their 
softness  and  the  hardness  of  the  Niagara  limestone  guided  the 
erosive  agents  in  making  the  escarpment  and  the  lower  plain. 

Over  all  this  rocky  foundation  lies  a  mantle  of  loose  material. 
— clay,  sand,  gravel,  and  bowlders, — collectively  called  the  driji. 
Its  ordinary  thickness  is  thirty  or  forty  feet ;  but  there  ai'e  places, 
especially  on  top  of  the  escarpment,  where  it  is  nearly  absent,  and 
elsewhere  it  fills  hollows  or  is  built  into  hills  -with  a  thickness  of 
several  hundred  feet.  It  was  spread  over  the  country  after  the 
broader  features  of  the  topography  had  l>eeu  shaped,  and  the 
agency  l>y  which  it  was  dei)Osited  was  nlO^"ing  ice,  as  will  be 
explained  a  little  later. 


THE    EIVEK    AND   THE   GORGE. 

From  Lake  Erie  the  Niagara  Eiver  runs  over  a  low  sag  in  the 
ridge  of  Corniferous  limestone.     Where  the  current  crosses  this 

rocky  barrier,  it  is  rajad  and  dis- 
turbed. Thence  for  fifteen  miles 
it  flows  alxive  shales,  but  rarely 
touches  them,  the  banks  and  bed 
consisting  chiefly  of  drift.  The 
channel  is  In'oad,  and  the  water 
glides  along  viith  unruflied  sur- 
face. Then,  a  little  below  the 
mouth  of  Chippewa  Ci'eek,  the 
Niagara  limestone  api>eai-s  in  the 
bed,  and  the  whole  habit  of  the 
stream  is  quickly  changed.  For 
a  thousand  yards  it  is  a  broad, 
roaring  rapid,  tumliling  over  one 
ledge  after  another  with  tunmltu- 
ous  haste;  and  then  it  pours 
over  a  precipice  to  the  bottom 
of  a  narrow,  deep,  steep-walled 
gorge.  For  seven  miles  it  courses, 
with  alternation  of  deep,  boiling 


Fio.  4.  —  Biril's-eye  View  ot'  th 
agara  River  from  Lake  (!)utario. 


Ni- 


Be-  pools  and  narrow,  violent  rai)ids, 

yoiul  the  Ontario  fihore  are  tlie  Lower  thrOUgll    this    gOrgC,   wllOSe     steei) 
Plain.  Escariiinenf.  I'pper  Plain,   and  ,,    '^  ..  ,    '^t     '"  i  , 

Lake  Erie.  walls  ot  rock  tljeii  turu  abruptly 


THE   lUVER   AND   THE   GORGE.  209 

to  the  right  aud  left,  and  merge  with  the  face  of  the  esearp- 
meut.  Thence  to  Lake  Ontario  the  width  is  moderate,  and  the 
current  is  strong  and  deep  between  steep  banks  of  red  shale 
capped  with  drift. 

Thus  for  two  thirds  of  its  journey  across  the  upper  plain  the 
river  travels  on  top  of  the  plain,  and  then  for  the  remaining 
third  it  runs  from  two  hundred  to  three  hundred  feet  below  the 
plain  in  a  narrow  trench.  This  contrast  is  the  geographic  fact 
on  which  scientific  interest  in  Niagara  has  centered,  and  its  im- 
portance is  not  readily  overestimated. 

The  walls  of  the  trench  are  vertical  clitfs  in  their  upper  part, 
and  are  there  seen  to  be  composed  of  the  same  limestone  that 
underlies  the  plain.     The  limestone  cliffs  are  of  moderate  height, 


Fig.  5.  — Cross  Seetions  of  Niagara  River. 

n,  two  miles  below  tbe  escarpnient ;  6,  in  the  narriiwest  part  of  the  jjorge ;  c,  iu  a  limad  part  of 
the  gorge ;  </,  two  iiiik's  alio\e  thu  falls.    Scale,  about  2,000  feet  =  1  iucli. 

and  from  their  base  there  usually  starts  a  talus  or  apron  of  frag- 
ments, which  descends  to  the  river's  edge.  The  general  appear- 
ance of  the  gorge  is  fairly  illustrated  by  the  view  in  Fig.  7.  Heiv 
and  there  the  talus  is  scant  or  altogether  absent,  so  that  tlic 
strata  can  be  seen;  and  wherever  they  can  ])e  seen,  examination 
shows  the  two  sides  to  have  the  same  l)eds,  in  the  .same  order, 
and  at  the  same  heights.  First  come  gray  shales  about  fifty  feet 
thick ;  then  a  Ijlue-gray  limestone  full  of  fos.sil  shells,  and  ten  or 
fifteen  feet  thick.  This  is  the  Clinton  limestone  of  geologists; 
and  it  is  so  firm,  as  compared  with  the  beds  immediately  above 
and  below  it,  that  rain  and  fi'ost  have  affected  it  less,  and  it 
projects  beyond  its  neighbors.  There  are  several  places  where 
the  edge  of  the  bed  is  a  cliff,  though  the  adjacent  shales  are 
covered  by  fallen  fragments  (Fig.  6).  -Next  below  are  gi-een-gray 
shales,  with  thin  limestone  beds,  and  a  soft,  gray  sandstone,  the 
whole  occupying  a  vertical  space  of  about  thirty  feet ;  and  then 
the  color  changes  to  a  Ijright  red,  which  characterizes  the  lower 
beds.  The.se  are  chiefly  shales,  liut  there  are  soft  sandstones 
among  them;  and  there  is  one  hard  sandstone  bed,  of  a  pale 


210 


NL'.GAKA   FALLS   AND   THEIR   HISTOKY. 


gray  color,  Avhicli  stands  out  iironiiiiently  like  the  Clinton  lime- 
stone, and  for  the  same  reason.  It  is  twenty  feet  or  more  in 
thickness,  lies  one  hundred  and  twenty  feet  below  the  Clinton 
limestone,  and  is  called  the  qnartzose  sandstone  (see  Figs.  10  and 
21).  The  observer  who  sees  these  various  rocks,  hard  and  soft, 
gray  and  red,  matched  bed  for  bed  on  the  ojiposite  sides  of  the 


Fig.  C. — Cliff  and  Talus  of  Aiiierieau  Bank  above  the  'Wliirlpool. 

The  Xiatrara  liiuestoui'  appears  in  the  upper  oliff;  the  Cliutou,  iu  the  lower.    The 
quartzoee  saudstonc  is  not  seen,  beiuK  below  the  water. 

gorge,  and  who  studies  them  at  the  angles  of  the  walls,  so  as  to 
realize  that  each  is  a  great  level  jilate,  which,  if  continued  through 
the  air,  would  bridge  the  chasm  to  its  companion  in  the  opposite 
waU,  never  doubts  that  the  rock  lieds  were  oi'igiually  continuous, 
and  that  the  gorge  is  of  later  origin.  As  to  the  way  iu  which 
the  gorge  was  made,  there  has  been  some  difference  of  opinion. 
One  or  two  writers  have  thought  it  was  a  crack  of  the  earth 
^•iolently  rent  apart,  and  one  or  two  others  have  thought  it  was 
washed  out  by  ocean  tides;  but  the  prevailing  opinion  is  that  it 
was  made  by  the  liver  that  flows  through  it,  and  tliis  opinion  is 
so  well  grounded  that  it  is  hardly  worth  while  to  consider  its 
rivals  iu  this  place.  The  agency  of  the  river  is  shown  by  the 
modern  recession  of  the  cataract,  liy  banks,  terraces,  gravels,  and 
shells,  marking  earlier  positions  of  the  liver  bed,  and  by  a  cliff 


THE   RECESSION    OF    THE   CATAKACT. 


211 


over  which  ijavt  of  the  liver  ouce  poured  as  a  cataract.  It  is 
qualified  by  a  buried  channel  belonging  to  an  earlier  and  differ- 
ent system  of  drainage.  As  these  evidences  are  intimately  con- 
nected with  the  history  of  the  cataract  and  livei-,  they  will  be  set 
forth  somewhat  fully. 

THE  RECESSION    OF   THE   CATARACT. 

Modern  Recession. — The  cataract  is  divided  unequally  by 
Goat  Island.  The  part  on  the  southwestern  or  Canadian  side  is 
the  broader  and  deeper,  and  is  called  the  Horseshoe  Fall ;  the 


i-'ii 


-The  UuriTL'   bclu'.v   lln 


Wliirli.uul,  with   i'lirl 
Foreground. 


■I      llil'     Wllllll'Hil 


Other  is  the  American  Fall.  As  shown  by  the  map  (Fig.  15),  the 
Horseshoe  Fall  is  at  the  end  of  the  gorge ;  the  American,  at  its 
side.  The  cliff  over  which  the  water  jwurs  is  from  one  hundred 
and  forty  to  one  hundred  and  seventy  feet  high,  measui-cd  from 
the  water  of  the  i-iver  below.  It  is  composed  of  the  Niagara 
limestone  at  top,  from  sixty  to  eighty  feet  thick  ;  and  the  shales, 


21J 


NUGAIJA   FALLS   AXD   THEIlt    HISTOUY. 


etc.,  beneath,  as  already  described.  At  the  edge  of  each  fall, 
where  one  can  look  for  a  distauce  under  the  sheet  of  desceudiug 
watei",  th(>  limestone  projects  like  a  cornice  beyond  the  •wall  of 


Fig.  S.  — The  Horseshoe  Fall,  from  the  Cauadiaii  Bank. 

shale;  so  that  there  is  a  stiip  of  the  upper  rock  which  is  not 
directly  supported  by  the  lower,  but  is  sustained  by  its  own 
strength.  From  time  to  time  portions  of  this  cornice  have  been 
seen  to  lireak  away  and  fall  into  the  \wo[  of  water  below,  and 
other  fallings  have  made  themselves  known  by  the  earth  tremors 


Fig.  9.  — The  Am. 


lU   i'aii.  Irum    tiic   (  ;iu;uH:iu   BaiiK. 


they  produced.  Usually  the  falling  masses  have  been  large ;  so 
that  their  subtraction  has  produced  conspicuous  changes  in  the 
contour  of  the  cataract,  and  their  dimensions  have  Ijeen  esti- 
mated in  scores  of  feet.  Nearly  all  liave  broken  from  the  cliff 
under,  or  at  the  edge  of.  the  Horseshoe  Fall.  As  these  catas- 
trophes depend  on  the  iirojection  of  the  limestone  ^^•ithont  sup- 


THE   KECESSIOX    OF   THE   CATABACT. 


•213 


port,  ^ve  are  warranted  in  supposing  that  it  is  gradually  depriveil 
of  support  by  the  removal  of  the  softer  rocks  beneath ;  and,  al- 
though it  is  impossible  to  see  what  takes  place  amiil  the  feaif ul 
rage  of  waters,  we  may  properly  infer  tlint  that  very  vioh^nce 
makes  the  cataract  an  engine  of 
destruction  by  which  the  shales 
are  battered  and  worn  away. 
Under  the  middle  of  the  Horse- 
shoe, where  the  pouring  sheet  is 
at  least  twenty  feet  thick,  its 
force  is  so  great  as  to  move  most, 
or  perhaps  even  the  largest,  of  the 
fallen  blocks  of  limestone,  and  by 
rolling  them  about  make   them 


serve  as  weajjons  of  attack. 


Fig.  lU.  — I'l-ofile  ami  Set-tioii  at  Mid- 
dle of  Hoi'seslioc  Fall,  showing  Anauge- 
In    1S27    Capt.    Basil    Hall,    of    ment  of  Uoi'ks  and  I'l-olialde  Depth  of 

the  British  Navy,  made  a  care-  ^''."''  "'"^^■■'  '•'"■  ,.       ,. 

'  '  N.I,.,  Niairara  Inuesttiiii' ;  CM...  Clinton  lime- 

ful     drawiuy     of     the     Horseshoe         stone ;  CJ.S..  (luartzo.si- sandstone.    Bcale, 
C'  3U0  feet  =  1  Inch. 

Fall  by  the  aid  of  a  camera  lucida. 

The  use  of  that  instrument  gives  to  his  drawing  a  quality  of 
accuracy  which  constitutes  it  a  valualjle  record.  Sixty-eight 
years  afterward,  in  1895,  a  photograph  was  made  from  the  same 
spot,  and  our  illustrations  (Figs.  11  and  12)  bring  the  two  pic- 
tures together  for  comparison.  The  bushes  of  his  foreground 
have  grown  into  tall  trees  which  restrict  the  view,  l>ut  the  re- 
gion of  greatest  change  is  not  concealed.  A  vertical  line  has 
been  drawn  through  the  same  point  (Third  Sister  Island)  in  each 
picture  to  aid  the  eye  in  making  the  comparison.  The  conspic- 
uous changes  are  the  broadening  of  the  gorge  by  the  falling- 
away  of  its  nearer  wall,  and  the  enlargement  of  the  Horseshoe 
curve  both  by  retreat  to  the  right  and  by  retreat  in  the  direction 
away  from  the  spectator.  In  1842  Professor  James  Hall,  State 
geologist  of  New  York,  made  a  careful  instrumental  survey  of 
the  cataract  for  the  jiuri»ose  of  I'ecording  its  outline,  .^o  that  sub- 
sequent recession  might  l>e  accurately  measured  l>y  means  of 
future  surveys.  His  work  has  been  repeated  at  -various  times 
since,  the  last  survey  l)eing  by  Mr.  A.  S.  Kibbe,  assistant  State 
engineer,  in  1890.  The  outlines,  as  determined  by  these  surveys, 
are  reproduced  in  the  chart  on  page  216  (Fig.  18),  which  shows 
that  the  greatest  change  has  occurred  in  the  middle  of  the  Horse- 
shoe curve,  where  the  thickness  of  the   descending  stream  is 


n4 


NIAGARA    FALLS   AND   THEIi;    HISTORY. 


THE    KECESSION    OF    THE    CATAKACT. 


21G 


XIAGAKA  FALLS   AXl)   THEIU   HISTORY. 


Fig.  13.  —  Outlines  of  the  Ci-est 
of  the  Horseshoe  Fall. 

The  vertical   and   horizontal   lines 
are  2tX)  feet  apart. 


greatest.  In  that  regiou  about  two  huiidved  and  twenty  feet  of 
the  limestone  bed  have  been  earned  away,  and  the  length  of  the 
gorge  has  been  increased  by  that  amount.     From  these  data  it 

has  boon  computed  that  the  cataract 
is  making  the  gorge  longer  at  the  rate 
of  between  four  and  five  feet  a  year, 
and  the  general  fact  determined  by  the 
observation  of  faUmg  masses  and  the 
comparison  of  pictures  thus  receives 
a  definite  expression  in  the  ordinary 
tenns  of  time  and  distance. 

The  agent  which  has  wi-ought  such 
important  changes  during  the  brief 
period  to  which  careful  observation 
has  been  limited  is  manifestly  able  to 
hoUow  out  the  entire  gorge  if  only 
granted  enough  time,  and  the  theory 
which  ascribes  the  making  of  the  gorge  to  the  work  of  the  falling- 
water  is  thus  strongly  supjiorted. 

Mode  of  Recession. — Before  passing  to  other  facts  bearing 
on  this  point,  it  is  well  to  caU  attention  to  certain  peculiarities 
of  the  process  whereby  it  difl:ers  from  the  nonnal  process  of 
cataract  erosion.  Pure  water  has  little  jiower  to  erode  solid 
rock.  It  can  pick  uj^  loose  particles  or  roll  them  along;  but 
Ann,  coherent  rock  cannot  be  broken  by  so  soft  a  tool.  Rock 
is,  indeed,  worn  away  by  rivers,  and  the  erosion  accomplished 
in  this  way  is  enomious ;  but  the  water  does  it  indii*ectly  by 
carrying  along  rock  fragments  which  rub  and  pound  the  solid 
rock  of  the  river  bottom.  The  rock  fragments  are  of  the  same 
material,  generally  speaking,  as  the  solid  rock,  and  they  wear  it 
away  just  as  diamond  dust  wears  the  solid  gem.  As  already 
pointed  out,  the  Niagara  is  peculiar  in  that  its  cm-rent  carries 
no  rock  fragments.  The  geographic  work  peiformed  by  the 
cataract  is  jn-actically  dependent  on  the  tools  furnished  by  the 
blocks  of  fallen  limestone.  It  is  therefore  of  prime  importance 
to  the  work  of  the  cataract  that  it  shall  be  able  to  roU  the  lime- 
stone fragments  about,  and  thus  grind  them  against  the  river 
bed.  A  .study  of  the  different  parts  of  the  cataract,  comparing 
one  ^with  another,  shows  that  the  water  has  this  power  only 
where  its  body  is  great ;  namely,  in  the  middle  part  of  the  Horse- 
shoe curve.     Under  each  edge  of  that  fall  and  under  the  Amer- 


THE   HECESSIOX   OF   THE   CATAKACT. 


217 


ican  Fall  great  blocks  of  limestone  lie  as  they  have  fallen,  mani- 
festly too  large  to  be  moved  by  the  moderate  streams  that  Vjeat 
against  them.  Some  of  these  are  shown  in  the  genei-al  view  of 
the  Horseshoe  Fall  (Fig.  8),  and  more  clearly  in  the  view  of  the 
Ameiicau  Fall  (Fig.  9).  The  block  at  the  extreme  right  of  the 
Ameiican  Fall  is  also  pictured  in  Fig.  14.  The  resistance  opposed 
by    these    blocks    makes  -  - 

the  I'ate  of  erosion  of  the 
Ameiicau  Fall  compara- 
tively sloAv.  In  fact,  it  is 
so  slow  that  attempts  to 
measure  it  have  thus  far 
been  unsuccessful,  be- 
cause the  changes  which 
have  taken  place  in  its 
outline  between  the  dates 
of  surveys  have  been  little 
greater  than  the  inaccu- 
racies of  the  surveys. 
Where  the  heaviest  body 
of  water  pours  down,  the 
blocks  are  not  mereh' 
moved,  but  are  made  to 
dig  a  deep  hollow  in  the 
shale.  The  i>reeise  depth  cannot  l)t'  measure(l,  because  the  mo- 
tion of  the  water  is  there  too  violent  for  sounding ;  but  a  little 
farther  down  the  rivei',  where  the  cataract  perfomied  its  woi-k 
only  a  few  centuries  ago,  the  plummet  shows  a  depth  of  neaiiy 
two  hundred  feet,  and  it  is  proba])le  that  the  hollow  directly 
under  the  Horseshoe  is  not  shallower  than  .that.  The  general 
fact  ai)pears  to  be  that  in  the  center  of  the  main  stream  the 
water  digs  deeply,  and  the  Ijrink  of  the  fall  recedes  rapidly. 
After  the  gorge  has  been  lengthened  by  this  process,  it  is  some- 
what widened  by  the  falling  in  of  its  sides;  and  this  falling  in 
is  in  a  measure  aided  by  the  thiinier  water  streams  near  tlie 
banks,  which  clear  away  the  smaller  limestone  fragments,  though 
leaWng  the  larger.  After  the  cataract  has  altogether  passed, 
the  cliff  is  further  modified  by  frost.  The  wall  of  shale,  being 
wet  by  spray  or  rain,  is  exposed  to  the  cold  air  of  winter,  and 
the  water  it  contains  is  frozen.  The  expansion  of  freezing 
breaks  the  rock,  either  crumbling  it  or  causing  flakes  to  fall 


i'li..  14.  — Th.'   -K.n-k  ul  Agi-N"  :t   Falliji  lllovk 

of  Niagara  Limestone  at  the  Soiitheni  Edge 

(if  tlie  Aineriean  Fall. 


218 


XIAGAKA   FALLS   AXD   THEIK    HISTORY. 


away.  lu  this  way  the  shale  is  eatou  Itaek,  and  the  Uiuestoiie 
above  is  made  to  fall,  uutil  enough  fallen  fiagments  have  been 
accumulated  to  protect  the  remainder  of  the  shale  from  frost, 

after  which  time  the  process  of 
change  becomes  exceedingly  slow. 
Thus  two  different  modes  of 
cataract  recession  are  illustrated 
by  the  two  faUs  of  Niagara.  They 
resemble  each  other  in  the  most 
essential  particiUar, — that  the 
soft  shale  beneath  is  worn  away, 
and  the  hard  limestone  above 
falls  for  lack  of  supi^ort, —  Itut 
they  differ  widely  in  other  re- 
spects. In  the  recession  of  the 
Horseshoe  Fall,  the  blocks  of 
limestone  are  pestles  or  gnnding 
tools  by  which  the  shale  is  beaten 
or  scoured  away.  In  the  reces- 
sion of  the  American  Fall,  the 
limestone  blocks  have  no  active 
share,  but  are  rather  obstructive. 
The  falling  water,  striking  them, 
is  splashed  against  the  cUft',  and 
this  splashing  is  the  only  foi'ce 
continually  applied  to  the  shale. 
In  the  spring,  ice  cakes  are  drifted 
from  Lake  Erie  into  the  entrance 
of  the  river,  and  float  to  the  falls. 
Borne  with  the  water,  they,  too, 
nmst  be  dashed  against  the  cliff 
of  shale,  and,  though  softer  than 
the  shale,  they  probably  helj)  to 
dislodge  it.  The  recession  in  one 
case  is  far  more  rapid  than  in  the 
other,  the  difference  being  explained  piimarily  by  the  difference 
in  the  volimie  of  the  water. 

Old  ErvEK  Baxks  axd  Gka^'els.  —  As  just  explained,  the  re- 
treating cataract  lengthens  the  gorge  most  rapidly  in  the  middle 
of  the  stream,  where  the  water  is  deepest.  As  the  gorge  is  ex- 
tended, the  current  turns  toward  its  head  from  Ijoth  margins. 


^ 

^ 

1 

jl 

^f^-^ 

\          ^'/ffJ 

^fp> 

Voster     f§X// 

1 

~^    ^"^5^         Wl  -^v"^^^ 

^---,         T*^     ^^hirlpool 

■^                  j              \^^  !*hrrlpool  Rapids 

7       /I " "  ° 

lagei 

J  if 

y»   >*....»t.  8..ag. 

■    m       ^vi^American  F*II 

^ftrs«  shoe  •■  I     ^  ^"^^^^  ^-ihr- 

fill  ;\ri^i!i^  ^—^^ 

X___ 

\%    Upp,r     ' 

^=53. 

"                  '^-'-     ^^^             '1 

Fig.  15. — The  Xiagara  Gorge,  showing 
Physical  Featui'es. 

Old  river  banks  are  shown  by  dotted  lines ; 
shell  localities,  by  crosses. 


THE   RECESSION   OF   THE  CATARACT. 


•Jl!> 


and  portions  of  the  river  bed  on  citlicr  side  are  thus  fjjradually 
abandoned  by  the  watei-.  After  these  strips  of  rivei-  V)ed  liave 
become  dry  hind,  they  retain  certain  featnres  by  which  tliey  can 
be  recognized.  Usually  the  whole  of  the  di-it't  is  washed  away  as 
far  as  the  water  extended,  so  that  the  rock  is  1)are,  or  nearly  bare ; 
and  the  edge  of  the  undisturbed  drift  at  the  margin  of  this  strip 
of  bared  rock  has  a  steep  slope,  which  so  closely  resembles  the 
modern  banks  of  the  river  above  the  cataract  that  the  imagina- 
tion readily  restores  the  former  outline  of  ihe  \vati*r  (see  Fig.  1(>). 


1'..   -u;a  i...L.  r...: 


Kiver  Be<l,  One  Mile  North  of  Ana-iifiiu  Fall. 


Sometimes  the  I'iver,  after  running  for  a  while  at  one  level,  has 
been  drawn  down  to  a  lower  level,  and  the  change  has  caused  a 
second  bank  to  be  produced,  the  space  between  the  first  and 
second  banks  standing  as  a  bench  of  land,  or  terrace.  At  some 
points  thei'e  ar(»  two  or  three  such  terraces.  Along  the  greater 
l)ai-t  of  the  gorge  these  old  banks  can  1)e  found  on  both  sides, 
and  there  ai'e  few  spots  where  they  do  not  survive  on  one  side 
ov  the  other.  The  farthest  point  to  which  tliey  can  be  ti'aced 
downstream  is  about  half  a  mile  tVnm  the  end  of  the  gorge,  and 


•2'2() 


NIA(;AKA    falls    and    THEIK    HlSIOltY. 


they  thus  serve  to  show  that  all  the  veniaiiider  of  the  gorge  has 
heeu  wrought  during  the  life  of  the  river;  for  it  is  evident  that 
the  river  could  not  run  on  tlie  ujihuul  while  the  gorge  was  in 
existence. 

In  a  few  cases,  where  the  top  of  the  limestone  lies  rather  low, 
the  old  river  beds  are  not  excavated  down  to  the  rock,  but  their 
terraces  are  |)artly  carved  in  drift.  In  yet  other  places  the  old 
river  not  only  carried  away  material,  but  made  additions,  leav- 
ing a  deposit  of  gravel  and  sand  that  had  been  rolled  along  l)y 
the  current.  In  this  gravelly  de]iosit,  shells  have  been  found  at 
a  number  of  places,  and  tlicy  are  all  of  such  kinds  as  live  in  the 
(piieter  parts  of  the  river  at  the  present  time. 

On  the  chart  on  page  218  (Fig.  1'))  the  most  important  of  the 
old  river  banks  are  shown,  and  also  a  number  of  spots  at  which 
shells  have  been  found  in  the  river  gi-avels. 

Foster  Flats. — Al)out  two  miles  and  a  half  soiith  of  the 
escarpment  the  goi'ge  assumes  a  peculiar  phase  not  elsewhere 
seen.  It  is  imusually  wide  at  the  top;  but  the  river  is  quite 
narrow,  and  runs  close  under  the  cliff  on  the  eastern  or  American 
side.  On  the  ('anadian  side  an  irregular  lowland  lies  Itetween 
the  cliff  and  the  river,  but  this  is  encroached  on  by  a  quadran- 
gular projection  of  the  cliff.     The  lowland  is  Foster  Flats;  and 


Fi'i.  17.  —  Binrs-i've  View  of  Foster  FlatK,  lonkiiif;  Soutliwest  (Forests  omitted). 


THE   KECESSIOX    OF  THE   CATAKACT. 


the  clilif  pvojectioii,  Wiiitergveeii  Flat.  These  and  other  features 
of  the  locality  are  portrayed  in  the  bird's-eye  view  (Pig.  17),  and 
also  in  the  map  (Fig.  IS).  The  niaj)  represents  the  slopes  of  the 
land  l»y  means  of  contour  lines,  or  lines  of  ecpial  height,  drawn 
at  vertical  intervals  of  twenty  feet. 

Wintei'green  Flat  is  a  platform  of  limestone  a  little  hdowthe 
genei'al  level  of  the  jdain,  and  separated  from  the  j)laiu  hy  a 
steep  hluff.  This  l)lufit'  is  one  of  the  old  I'iver  banks,  very  simi- 
lar to  the  one  pictured  in  Fig.  Ki,  and  the  i)latform  is  part  of  the 
river's  l)e<l.  Following  the  direction  of  How — jiai-allel  to  the 
bank — to  the  point  A  (Fig.  IX),  the  observer  finds  himself  on 
the  brink  of  a  cliflf  over  which 
the  water  evidently  descended 
in  a  cataract ;  and  before  him, 
extending  from  the  foot  of  the 
cliff  to  the  point  />',  is  a  de- 
scending valley  with  the  form 
of  a  river  1  n^d.  From  Winter- 
green  Flat  onlj^  its  general 
shape  can  be  made  out,  as  it 
is  clothed  with  forest;  but 
wlien  one  gets  down  to  it,  he 
finds  it  a  northward-sloping 
]ilain,  bounded  by  steej)  sides, 
and  strewn  here  and  there  with 
great  fallen  blocks  of  lime- 
stone which  the  river  current 
could  not  remove.     The  left 


Fio.  18.  — Map  of  Foster  Flats. 


bank  of  this  channel  has  the  ordinary  ])rofile  of  the  wall  of  the 
gorge, — a  cliff  of  the  Niagara  limestone  at  top  and  a  talus  slope 
below,  covered  by  blocks  of  tlu^  same  rock.  The  right  wall  is 
lower,  rising  at  most  but  fifty  feet  above  the  channel,  and  gra<lu- 
ally  disaiijicaring  northward.  Tt  is  merely  the  side  of  a  low  ridge 
which  separates  the  abandonc(l  channel  from  the  river  bed  at 
the  cast.  Its  siirface  is  exceedingly  rugged,  being  covered  by 
huge  blocks  of  limestone,  so  that  the  ridge  seemingly  consists  of 
a  heap  of  them ;  but  then^  is  doubtless  a  nucleus  of  undistiu'bed 
shale,  with  a  remnant  of  the  Clinton  ledge.  EastM-ard  from 
Wintergreen  Flat  there  is  a  continuous  descent  from  the  lime- 
stone cliff'  to  th(>  river;  but  this  is  less  stee])  than  the  ordinary 
talus  slope  of  the  gorge,  and  it  is  cumbered,  like  the  ridge,  by 


lljL'  NIAGAKA    FALXS    AND   THUlIt    HISTORY. 

liloi'ks  of  liinestouo.  Theio  is  an  obscure  tevraoe  at  about  the 
level  of  tli»'  Clinton  limestone,  and  there  are  other  irregular  ter- 
races on  the  st)Uth\vard  prolongation  of  the  slope. 

The  history  which  appears  to  afford  the  best  explanation  of 
these  features  is  as  follows :  When  the  cataract,  in  its  recession 
fi'oni  the  escaipment,  had  reached  the  point  L',  it  was  a  broa<i 
waterfall.  Just  above  it,  occupying  the  position  (' — 1),  was  a 
narrow  island,  dividing  the  river  as  Goat  Island  now  divides  it. 
On  reaching  the  island,  the  cataract  was  sepai-ated  into  two 
parts  corresponding  to  the  present  Horseshoe  and  American 
falls,  only  at  that  epoch  the  greater  body  of  water  passed  on  the 
Anici-ican  side  of  the  island,  so  that  the  American  Fall  retreated 
upstream  the  more  rapidly.  When  the  Cauadian  Fall  reached 
the  head  of  the  island,  the  American  had  just  passed  it,  and  part 
of  the  sheet  of  water  on  Winteigreen  Flat  was  drained  eastward 
into  the  gorge  opened  by  the  American  Fall.  The  Canadian 
Fall,  through  the  loss  of  this  water,  became  less  active,  and  soon 
fell  out  of  the  race,  leaAnug  the  cliff  at  A  to  record  its  defeat. 
For  a  time  there  was  a  cataract  at  E  falling  oA-er  the  west  wall 
of  the  gorge  just  as  the  modern  American  cataract  falls  over  the 
east  wall.  The  island  was  not  bi'oad  enough  to  survive  as  a 
mommient.  After  the  cataracts  had  passed,  its  pedestal  of  shale 
was  crumbled  by  the  frost,  and  the  unsupported  limestone  fell 
in  ruins.  As  the  main  fall  retreated  still  farther,  the  western 
portion  of  the  water  sheet  was  withdrawn  from  "Wintei'green 
Flat,  occui)ying  a  position  at  F,  and  at  the  same  time  the  stream 
near  the  Canadian  shore  acquired  greater  volume,  so  as  to  i-ecede 
rapidly  toward  G  and  thus  broaden  the  channel.  Pro])ably  at 
about  the  same  time  the  whole  amount  of  watei'  in  the  river  was 
increased  in  a  manner  to  be  considered  latei'. 

"\^Tien  the  reader  next  visits  Niagara,  he  will  find  himself 
fully  repaid  for  his  pains  if  he  will  go  to  this  spot,  and  examine 
these  features  for  himself.  It  is  peculiarly  impressive  to  stand 
on  the  silent  brink  of  the  old  wateifall  and  look  down  the  diy 
channel,  and  it  is  no  less  impressive  to  enter  that  channel  and 
wander  among  the  blocks  of  rock  Avhich  record  the  limit  of  the 
torrent's  power  to  transport.  It  is  evident  that  here  the  cataract 
did  not  hollow  out  a  deep  pool,  as  under  the  Horseshoe  Fall  of 
to-day,  but  was  rather  comparable  in  its  mode  of  action  to  the 
American  Fall,  though  perhaps  somewhat  more  vigorous.  The 
slope  eastward  from  Wintergreen  Flat  probably  corresponds 


THE   KECESSIUN   OF   THE   CATAKACT.  JJ.'J 

closely  with  what  oue  woukl  hud  under  the  Amerieau  Fall  if  the 
rivev  were  stopped  aud  the  pool  drained. 

Thus  Foster  and  Wintergreen  flats  repeat  the  story  told  by 
the  old  river  banks  and  the  shell-bearing  gravels.  There  was  a 
time  when  there  was  no  gorge,  but  when  the  i-iver  i-au  over  the 
top  of  the  plain  nearly  to  its  edge ;  and  since  that  time  the  gorge 
has  been  gradually  dug  out  by  tlie  power  of  the  jilunging  water. 

Beiunning  of  Kecessiox. — When  the  geogi'aphfi-  notes  that 
some  natural  process  is  producing  changes  in  the  features  of  the 
land,  he  naturally  looks  backward,  if  h(>  can,  to  see  what  were 
the  earlier  features  which  i»ivcedcd  the  changes  in  pi'ogress,  and 
looks  forward  to  see  what  will  be  the  eventual  condition  if 
changes  of  the  same  sort  are  continued.  The  tracing  of  the  his- 
tory of  change  in  either  direction  is  apt  to  be  difficult,  l)ecause 
it  is  not  easy  to  tell  what  allowances  to  make  for  changes  of  cir- 
cumstance or  condition.  In  tracing  the  early  history  of  Niagara 
such  difficulties  as  these  arise,  but  there  is  one  difficulty  which 
is  not  altogether  unfortunate,  because  it  leads  to  the  discovery 
that  the  Niagara  history  is  definitely  related  to  one  of  the  most 
interesting  events  of  the  geographic  development  of  the  conti- 
nent. 

Having  learned  from  tlic  cataract  that  it  is  engaged  in  the 
work  of  gorge  making,  and  having  learned  from  the  old  river 
beds  along  the  margins  of  the  gorge  and  fi'oni  the  old  cataract 
cliff  at  Foster  Flats  that  this  work  of  gorge  making  has  been 
carried  on  through  the  whole  length  of  the  gorge,  we  are  cari'ied 
back  in  imagination  to  an  ei)och  when  the  river  traveled  on  the 
upper  plain  all  the  way  from  Lake  Erie  to  the  escarpment,  and 
there  descended.  The  general  history  is  cleai'ly  traced  back  to 
that  point,  but  there  it  seems  to  stop  abruptly.  We  may  com- 
pare the  river  to  an  artisan  sawing  the  plateau  in  two.  The 
work  goes  on  mei-rily  and  the  saw  cut  is  still  short.  As  geolo- 
gists reckon  time,  it  is  not  long  since  the  task  Avas  begun.  But 
Nature's  artisans  cannot  stand  idle;  while  they  live,  they  must 
work.  So,  before  this  task  was  liegun,  either  the  stream  had 
some  other  task  or  else  there  was  no  Niagara  River.  It  seems 
impossible  to  suggest  any  otluM-  task,  and  all  geogi'ai)hers  are 
agreed  that  theiv  was  none.  The  river's  first  work  was  the  dig- 
ging of  the  gorge,  and  the  date  of  its  beginning  was  the  date  of 
the  river's  beginning. 

The  nature  of  this  beginning,  the  series  of  events  whii-h  led 


'2'2i  XIAtiAKA    I'AI.I.S    AND    TIIKIU    HISTOltV. 

Up  to  it,  Of,  ill  otluT  words,  the  ciUise  of  tiic  river,  was  long 
sought  ill  vain;  ami  an  interesting  cliapter  luiglit  lie  written  on 
tile  fruitless  search.  The  needed  light  Avas  an  understanding  of 
the  origin  of  the  drift;  aii<l  it  was  not  till  a  young  Swiss  geolo- 
gist, Louis  Agassiz,  brought  from  the  Alps  the  idea  of  a  drift- 
bearing  iee  field  that  the  discovery  of  Xiagnra's  jiedigree  became 
possible. 

PEVELOl'MENT    OF    THK    LAlltENTIAN    EAKES. 

The  Ice  Sheet. — The  history  of  the  great  Canadian  glacier  is 
a  large  subject,  to  which  some  future  monograph  of  this  series 
will  doubtless  be  devoted.  Any  account  t)f  it  whi<di  can  be 
given  here  must  needs  be  inade([uate,  yet  a  full  understanding 
of  Niagara  cannot  be  reached  without  some  knowledge  of  the 
glacier.  In  the  latest  of  the  geologic  periods  the  climate  of 
North  America  underwent  a  series  of  remarkable  changes,  be- 
coming alternately  colder  and  warmer.  While  the  general  tem- 
peratui-e  was  low,  there  was  a  large  area  in  Canada  over  which 
the  fall  of  snow  in  winter  was  so  deep  that  the  heat  of  summer 
did  not  fully  melt  it ;  so  that  each  year  a  certain  amount  was  left 
over,  and  in  the  course  of  centiiries  the  accumulation  ac(juired 
a  depth  of  thousands  of  feet.  By  pressure,  and  l>y  melting  and 
freezing,  the  snow  was  packed,  and  welded  into  ice.  When  the 
climate  again  became  warmer,  this  ice  was  gradually  melted 
away;  but  while  present  it  perfornie(l  an  imiiortant  geographic 
work.  Ice  in  large  masses  Is  plastic;  and  when  the  ice  .sheet 
had  become  thick,  it  did  not  lie  inert  and  motionless,  but  spread 
itself  outward  like  a  mass  of  iiitch,  its  edges  slowly  jiushing 
away  from  the  central  tract  in  all  diivctions.  This  juotion  car- 
ried the  ice  border  into  regions  of  warmer  climate,  where  it  was 
inelte(l;  and  for  a  long  ])eriod  there  was  a  slow  but  continuous 
movement  from  the  central  region  of  accumulation  to  the  mar- 
ginal region  of  waste  l)y  melting.  The  principal  region  of  ac- 
cumulation was  north  and  northeast  of  the  Great  Lakes,  and 
the  flowing  ice  jiassed  over  the  lake  region,  invading  all  our 
Northern  States.  Where  the  ice  jncssed  (m  the  grcmnd,  it  envel- 
o])ed  l)owlders,  pebbles,  and  whatever  lay  loose  on  the  suiface; 
and  as  it  moved  forward,  these  were  carried  with  it,  being 
dragged  o\er  the  solid  rock,  ami  scra])ing  it.  Thus  the  country 
was  not  merely  swept,  but  scratclie(l  and  jilowed,  with  the  result 
that  its  .surface  was  worn  down.     The  aniount  of  wear  was  not 


DEVELOPMENT   OF   THK    I.AIKENTIAN   LAKES.  2'J.) 

everywhere  the  same,  ))ut  varied  from  place  to  place,  and  many 
basius  were  hollow(^(l  imt.  AVIhmi  tln^  general  climate  Ijecanie 
gradually  warmer,  the  was^te  of  ice  near  its  margin  exc-eeded  the 
supply,  and  the  extent  of  the  sheet  was  diminished.  When  the 
ice  was  gone,  the  stones  and  earth  it  had  picked  up  and  ground 
up  remained  on  the  land,  hut  in  new  positions.  They  were 
sjiread  and  hea2)ed  irregularly  over  the  surface,  constituting  the 
mantle  of  di'ift  to  which  reference  has  already  been  made. 
Thus  by  the  double  process  of  hollowing  and  heaping,  the  fai-e 
of  the  land  was  I'emodeled;  so  that  when  the  rain  oiire  moiv  fell 
on  it,  and  was  gathered  in  sti-eams,  the  old  water  ways  were  lost, 
and  new  ones  had  to  be  found. 

This  remodeling  ga\'e  to  the  Laui'eiitian  system  of  watei- 
ways  its  abnormal  chai-actei-,  supplying  it  with  abundant  lakes 
and  waterfalls.  Not  only  wei'e  the  Great  Lakes  created,  l)ut  a 
multitude  of  minor  lakes,  lakelets,  ponds,  and  mai'shes.  if  the 
reader  will  study  some  good  map  of  the  rnite<l  States  or  of 
North  America,  he  will  see  that  this  lake  district  includes  New 
England  also,  and  1»y  tracing  its  (>xtent  in  othei'  tlirectioiis  he 
can  get  a  fail"  idea  of  the  magnitude  of  the  ice  sheet. 

The  lakes  have  had  a  marked  intluenc<'  on  the  history  and 
iuciustries  of  maidvind.  Still  water  ]nakes  an  easy  roadway,  and 
the  chain  of  (Jreat  T^akes  not  only  guided  exploration  and  early 
settlement,  but  has  (h'termined  the  chief  routes  of  commerce 
ever  since.  The  most  easterly  of  the  ice-made  basins,  instead  of 
holding  lakes,  receive  arms  of  the  sea,  giving  to  New  York  and 
New  England  some  of  the  l)est  harbors  in  the  world.  Each  cat- 
aract is  a  water  powei-,  and  the  lakes  and  ponds  upstream  ai-e 
natural  storage  ivservoirs,  holding  l»ack  Hoods,  and  doling  the 
water  out  in  time  of  drought.  So  Chicagc)  and  New  York  City 
are  the  centers  of  trade,  and  New  England  is  a  land  of  hum- 
ming spimiles  and  lathes,  becaus(>  of  an  invasion  long  ago  by 
(Canadian  ice. 

The  district  of  the  Niagara  lay  far  within  the  extreme  limit 
of  the  ice,  and  the  (b-ift  there  lying  on  the  rocks  is  part  of  the 
great  ice-spread  mantle.  Wherever  that  drift  is  freshly  removed, 
whether  by  the  natural  excavation  of  streams  or  the  artifi<'ial  ex- 
cavation of  (luarrymen  and  builders,  the  rock  l)eneatli  is  found 
to  be  polished,  and  covered  by  pai'allel  scratches,  the  result  of 
rubbing  by  the  ice  and  its  gritty  load.  These  scratches  show 
that  in  this  particular  district  the  ice  moved  in  a  direction  about 


L"Jt) 


NIAGAKA    FALLS  AND   THEIK    HISTOKY. 


30°  west  of  sdutli.  Tliey  can  lie  seen  on  tlie  western  l)vink  of 
the  gorge  four  hundred  yards  below  the  raihoad  suspension 
lii'idge,  in  the  beds  of  several  creeks  near  the  Whirl jxxvl,  and  at 
various  (juarries  above  the  es('ari)nH>nt.  The  l)est  oppoi-tunity 
to  study  them  is  at  a  group  of  quarries  near  the  brink  of  the 
eseai'pnient,  about  two  miles  wi^-^t  of  the  river. 

Ice-dammed  Lakes.  —  During  the  period  of  final  melting  of 
the  iee  sheet,  when  its  southern  margiu  was  gradually  retreating 
across  the  I'egion  of  the  (Ireat  Lakes,  a  number  of  temporary 
lakes  of  peculiar  character  were  formed.     In  the  accompanying 

sketch  map  of  the  Great  Lake 
region  (Fig.  19)  the  broken 
line  marks  the  position  of  the 
southern  rim  of  the  8t.  Law- 
rence basin.  It  is  the  water- 
shed between  the  district 
ilraining  to  the  St.  Lawi-ence 
and  the  contiguous  districts 
draining  to  the  Mississippi, 
Ohio,  Husquehanna,  and  Hud- 
son. When  the  ice  sheet  was 
^"'-  "n?^!;i;,Se  DiJ^r^r""  *'"'"       gi-^atest,  its  southern  mai-gin 

The  watershids  liouiidiiig  tlie  drainafre  (Ustviits     "^y    SOUtll    ot    tlllS    Watershed. 
;nvrepresen,...n,.vaotte,l  and  .n„k.„  lines.  rj.,,^     ^..^j^^     ^^.^^-^.j^     ^.^^,j     ^^^^     ^j^^ 

ice,  uniting  with  the  water  made  by  melting  ice,  ran  from  the 
ii-e  held  on  to  the  land,  and  flowed  away  with  the  rivers  of  the 
land.  Aftei-ward,  when  the  extent  of  the  ice  ha<l  been  some- 
Avliat  reduced,  its  margiu  lay  partly  beyond  and  paitly  within 
the  basin  of  the  lakes;  but  the  water  fi'om  it  could  not  flow 
<lown  the  St.  Lawrence,  ])ecause  that  valley  was  still  occu- 
l>ied  l)y  the  ice.  It  therefore  gathered  between  the  ice  front 
and  the  watershed  in  a  series  of  lakes,  each  of  which  found 
outlet  southward  across  some  low  jioint  in  the  watershed.  To 
see  this  clearly  may  require  some  eifort  of  the  imagination. 
The  reader  should  bear  in  mind  that  the  watershed  is  not  a  sim- 
ple ridge,  but  a  rolling  ui)land  f)f  varying  height,  with  here  and 
there  a  low  pass.  The  St.  Lawrence  basin  is  not  simple  and 
r<>gular  in  form,  but  is  made  up  of  many  smaller  l)asins  separated 
by  minor  uplands  or  watersheds.  Some  of  these  watersheds 
are  shown  on  the  map.  When  the  ice  occu]>ied  part  of  minor 
basins,  it  acted  as  a  dam,  holding  the  water  back,  ami  making 


DEVELOPMENT  OF  THE  LAURENTIAN  LAKES.         '2'27 

it  fill  the  basin  until  it  could  How  in  some  other  direction.  As 
the  position  of  the  ice  front  changed,  these  lakes  were  changed, 
being  made  to  unite  or  sepai'ate,  and  often  to  abandon  one  chan- 
nel or  outlet  when  another  was  opened  at  a  lower  level.  Some- 
times there  were  chains  of  lakes  along  the  ice  margin,  one  lake 
draining  to  another  across  a  minor  waterslied,  and  the  lowest 
discliarging  across  the  main  watershed. 

AVherever  water  rail  from  a  lake,  it  niodified  the  suiface. 
The  loose  drift  was  easily  moved  by  the  current,  and  each  stream 
(juickly  liollowt'd  out  for  itself  a  channe],  —  a  trough-like  passage 
with  flattish  bottom  and  steejj  sides.  When  tlie  lakes  afterward 
disappeared,  the  channels  lost  their  streams,  but  their  fonns  i-e- 
mained.  They  are  still  to  be  seen  in  a  hundred  passes  among 
the  hills  of  the  Northern  States.  The  larger  and  longer-lived  of 
the  lakes  carved  by  their  waves  a  still  more  conspicuous  record. 
In  ways  explained  by  Professor  Shaler  in  tlie  fiftli  monograph 
of  this  series,  the  waves  set  in  motion  liy  storms  cut  out  sti-ands 
and  cliffs  from  the  drift  and  Iniilt  up  barrier  beaches,  so  that 
after  the  lake  waters  had  dejiarted  there  were  terraces  and  ridges 
on  the  hillsides  to  show  where  the  shores  had  been.  Many  of 
the  old  channels  have  been  found,  some  of  the  old  shore  lines 
have  been  traced  out  and  marked  on  maps,  and  by  such  investi- 
gation the  history  of  geographic  changes  in  the  (ireat  Lake 
region  is  gi'adually  l^eing  learntMl. 

At  one  stage  of  that  history  there  was  a  long  lake  occupying 
the  western  part  of  the  Ontario  basin,  much  of  the  Erie,  pai-t  of 
the  Huron,  and  ]>robably  part  of  the  ^licliigan.  Its  outflow 
crossed  the  main  watershed  at  Chicago  {(\  Fig.  19),  and  its  east- 
ern extremity  was  near  Batavia  (/i)  in  westei-n  New  York.  The 
ice  mass  filled  the  greater  p.irt  of  the  Ontario  basin,  and  kept 
the  water  from  escaping  (>astward.  When  it  melted  from  that 
region,  the  water  shifted  its  outlet  from  Chicago  to  a  low  pass 
at  Rome  (R),  where  it  discharged  to  the  Mohawk  valley.  This 
change  lowei'ed  the  lake  surface  sevei-;il  liuudi'cd  feet,  and,  by 
uncovering  watorslieds  that  had  before  Iteeu  submerged,  sepa- 
I'ated  the  Huron,  Erie,  and  Ontario  basins,  and  three  lakes  took 
the  place  of  the  single  long  lake.  In  the  Huron  basin  was  a  lake 
half  walled  by  ice;  in  the  Erit;  basin.  Lake  Erie;  au<l  in  the 
Ontario  basin.  Lake  Irocpiois,  an  ice-dammed  lake  with  its  outlet 
at  Rome. 

The  draining  away  of  so  larg(>  a  body  of  water  occupied  some 


•2'2f<  XLiGAlU    FALLS    AND   THEIU    HISTOKY. 

time,  SO  that  the  lake  level  was  gvadiially  lowered.  Wiieu  it 
reached  the  i»ass  between  the  Erie  and  Outano  basins  at  Hutfalo, 
and  Lakes  Erie  and  Irociuois  were  thereby  i)arted,  the  Erie  level 
could  fall  no  lower,  but  the  Iroquois  eontiniied  ilowuward.  As 
soon  as  there  was  a  ditferenee  of  level,  a  stream  began  ti>  How 
tVoni  Lake  Erie,  and  that  stream  was  the  infant  Niagara,  newly 
born.  It  was  a  short  stream,  because  the  edge  of  the  Irotjuois 
water  was  close  to  Bulfalo ;  but  it  grew  longer  day  by  day,  as 
fast  as  the  Iroquois  edge  receded.  It  had  no  cliaunel  until  it 
made  one,  but  its  growing  end,  in  following  the  retreating  lake, 
selected  at  each  instant  the  direction  of  steepest  slojie;  and  as 
the  slopes  had  l)een  fonued  by  the  glacier,  it  may  lie  said  that 
the  glacier  predetermined  the  course  of  the  river. 

During  some  centuries  or  millenniums  of  its  early  life  the 
river  was  shorter  than  now,  because  the  Ircxjuois  Lakn  flooded 
more  land  than  the  Ontario,  and  kept  the  river  nearer  the  escarp- 
ment;  lint  in  cour.se  of  time  the  ice  dam  disappeared,  the  lake 
outlet  was  removed  from  Rome  to  the  Thousand  Islands,  part 
of  the  lake  bottom  was  laid  bare  by  th.e  retiring  water,  and  the 
river  stretched  itself  over  the  broadened  plain.  It  grew,  in  fact, 
to  be  a  few  miles  longer  than  now,  and  theiv  were  other  changes 
in  length  :  but  the  entii'e  story  is  too  long  and  intricate  for  these 
[lages. 

The  C'antim;  of  Baslns. — The  geographers  who  have  mapped 
the  glacial  lakes  by  tracing  their  shore  lines  have  also  measured 
the  heights  of  these  lines  at  many  jioints.  From  these  measure- 
ments they  have  found  that  the  lines  are  not  level.  The  surface 
of  each  ice-dammed  lake  wa.x,  of  course,  level,  and  its  waves, 
beating  on  the  shores,  carved  beaches  and  strands  all  at  the 
same  level.  But  these  abandoned  stran<ls.  preserved  as  terraces 
on  the  basin  slojies,  are  not  level  now  ;  and  it  is  therefore  inferred 
that  the  earth  itself,  the  rocky  foundation  on  which  the  terraces 
rest,  has  changed  its  fonn.  The  idea  of  earth  m()vements,  the 
slow  rising  of  some  districts  and  the  sinking  of  others,  is  not 
new:  but,  until  these  old  shore  Hues  were  stiuiied,  it  was  not 
known  that  such  changes  had  recently  affected  the  Lake  region. 

The  departure  of  the  old  shore  lines  from  horizontality  is  of 
a  sy.stematic  character.  They  all  rise  toward  the  north  and  east, 
and  fall  toward  the  south  and  west.  The  amount  of  this  tilting 
or  inclination  is  not  the  same  everywhere,  nor  is  it  everywhere 
in  precisely  the  same  direction;   but   the  general  fact   plainly 


DEVELOl'MENT   Ol'   THE   LACKENTIAN   LAKES.  2'2\) 

appears,  that  tlif  uoitln-astcin  jiortiou  of  the  Great  Lake  district 
has  been  raised  or  tlie  soutliwesteni  portiou  has  been  lowered,  <>i' 
l)otl),  several  limidred  feet  since  the  epoch  of  these  ice-dammed 
lakes,  i.e.,  since  the  time  when  the  Canadian  ice  sheet  Wiis 
slowly  nndting  away.  The  ett'ec-t  of  this  change  Avas  to  tip  oi- 
cant  eacli  lake  basin,  and  the  eflt'ect  of  the  canting  was  similar  to 
the  effect  of  canting  a  hand  l)asin  containing  water.  In  the 
hand  basin  the  water  rises  on  the  side  toward  which  the  basin  is 
tipped,  and  falls  away  on  the  opposite  side.  In  the  lake  basin 
thei'e  was  a,  constant  supply  of  water  from  rain  and  sti^'unis,  so 
that  it  was  always  filled  np  to  the  level  of  the  lowest  point  of  its 
rim,  and  the  surplus  of  water  flowed  away  at  that  jmint ;  .vo. 
when  it  was  canted,  the  changes  in  the  extent  of  the  lake  were 
partly  controlled  by  the  outflow.  If  the  outlet  was  on  the  north- 
eastern side  of  the  basin,  the  southwesterly  canting  would  make 
the  water  i-ise  along  its  southwestern  shore,  the  submerged  area 
being  thereby  enlarged.  If  the  outlet  was  toward  the  southwest, 
then  the  canting  woulil  draw  the  water  away  from  the  noilh- 
eastern  slopes,  and  diminish  Ihe  submerged  ai'ea.  if  the  lowest 
point  of  the  rim  was  originally  on  the  northeast  side,  the  canting 
might  lift  this  part  of  the  rim  so  high  that  some  point  on  the 
southwest  side  would  become  lowest,  and  the  ])oint  of  outlet  might 
thus  be  changed  fi'om  north  or  east  to  south  or  west.  The  evi- 
dence of  the  old  shores  and  channels  shows  that  all  these  possible 
changes  have  actually  occurred  in  the  lake  basins,  and  that  some 
of  them  Nvcrc  r(>late(l  in  an  important  wa\'  to  Ihe  history  of  the 
Niagara-  Kivei'. 

The  gi-adnal  canling  affected  the  size  of  l^ake  Erie,  Lake 
Ontario,  and  the  temporary  Lake  Irocpiois,  making  each  grow 
toward  the  southwest.  "When  Lake  Erie  was  born,  its  length 
could  not  have  lieen  more  than  half  as  great  as  now,  and  its  area 
was  much  smaller.  The  original  Lake  Huron  may  havt>  had 
about  the  same  size  as  the  present  lake,  but  its  form  and  position 
were  ditt'erent.  Less  land  was  covered  at  the  south  and  west, 
more  land  at  the  north  and  east,  and  the  outlet  was  at  North 
Bay  (iY,  Fig.  l!l).  I>y  the  tipping  of  the  basin  the  lake  was 
made  gradually  to  expand  toward  the  west  and  south  till  at  last 
the  water  reached  the  pass  at  the  head  of  the  8t.  Clair  Eiver. 
Soon  afterward  the  water  ceased  flowing  through  the  North  Bay 
outlet.  The  water  then  gradually  withdrew  from  the  northeast- 
ern region  till  finally  the  shores  assunu'd  their  present  po.sition. 


230  NUGAKA   FALLS   AXD   THEIR   HISTORY. 

At  au  earlier  stage,  while  the  North  Bay  district  was  blocked  by 
the  ice  sheet,  it  is  probable  that  the  basiu  had  au  outlet  uear 
Lake  Siim-oe  (.S'),  but  the  evidence  of  this  is  less  conii)lete.  If 
the  Hurou  water  crossed  the  basin's  rim  at  that  poiut,  it  followed 
the  Trent  valley  to  Lake  Iroquois  or  Lake  Ontario;  when  it 
crossed  the  rim  at  Xortli  Bay,  it  followed  the  Ottawa  valley  to 
the  8t.  Lawrence ;  and  in  each  case  it  i-eached  the  ocean  without 
passing  through  Lake  Erie  and  the  Niagara  River.  Thus  there 
was  a  time  when  the  Niagara  River  received  no  water  from  the 
Huron,  Michigan,  or  Superior  l)asins,  but  from  the  Erie  basin 
alone.  It  was  then  a  conipai'atively  small  stream,  for  the  Erie 
basin  is  only  one  eighth  of  the  whole  district  now  tributary  to 
the  river ;  and  the  cataract  more  nearly  resembled  the  American 
Fall  than  the  Horseshoe. 

THE    WHIRLPOOL. 

The  Whirlpool  is  a  peculiar  point  in  the  course  of  the  river. 
Not  only  does  the  channel  theie  make  an  abrupt  turn  to  the 
right,  but  with  equal  aliruptness  it  is  enlarged  and  again  con- 
tracted. The  pool  is  a  deep  oval  basiu,  communicating  through 
narrow  gateways  with  the  gorge  above  and  the  gorge  below. 
The  torrent,  rushing  with  the  speed  of  an  ocean  greyhound  from 
tlie  steep,  shallow  passage  known  as  the  Whirlpool  Rapids, 
enters  the  pool  and  courses  over  its  surface  till  its  headway  is 
checked.  The  initial  impulse  prevents  it  from  turning  at  once 
toward  the  channel  of  exit,  and  the  current  circles  to  the  left  in- 
stead of  the  right,  following  the  curved  margin  of  the  pool,  and 
finally  descending  under  the  entering  stream  so  as  to  rise  beyond 
it  at  the  outlet.  Thus  the  water  describes  a  complete  loop,  a 
peculiarity  of  curi'ent  (juite  as  remarkable  and  rare  as  the  feats 
of  railway  engineering  which  bear  that  name.  In  the  chart  of 
the  Whirlpool  (Fig.  'JO)  tlie  sui-face  cunvnts  are  indicated  l>y 
arrows ;  and  some  idea  of  the  appearance  of  the  currents  may  be 
obtained  from  the  view  in  Fig.  7,  where  the  swift  incoming  cur- 
rent crosses  the  foreground  from  light  to  left,  and  the  exit  cur- 
rent occupies  the  middle  of  the  picture.  In  the  smoother  tract 
between  these  two  visiljle  currents  the  wat»>r  rises  after  passing 
under  the  nearer.  These  cun-ents  can  be  watched  from  any  of 
the  surrounding  cliffs,  and  there  is  a  fascination  about  them  akin 
to  that  of  the  cataract  itself  and  the  Whiiipool  Rapids. 


THE    WHIKLPOOL. 


L':!l 


Fio.  a).— Tlie  Whirlpool. 

Roik  is  indicated  hy  ornsshnfcliiiiK;  drift, 

liy  dots.     Ari-ows  indicate  tlic 

direction  of  cui-rcnt. 


The  gorge  above,  tlic  gorge  below,  and  two  sides  of  the 
Whirlpool  are  walled  by  roek;  but  the  remaining  side,  that  op- 
posite to  the  incoming  stream,  shows  no  rock  in  its  wall  (Figs. 
20  and  '21).  On  the  north  side,  the  edge  of  the  Niagara  limestone 
can  be  traced  to  J  (Fig.  20)  with  all  its  usual  characters,  Init 
there  it  disappears  l)eneath  the  drift.  The  Clinton  limestone 
disappears  in  a  similar  way  just 
Vjelow  it,  and  the  quartzose  sand- 
stone, which  there  skii-ts  the  mar- 
gin of  the  water,  is  a  little  more 
quicklj'  covered,  being  last  seen 
at  11.  On  tlie  south  1)ank  tlie 
Niagara  limestone  can  be  traced 
farther.  Its  edge  is  visil)le  almost 
continuously  to  1%  and  is  laid 
bare  in  the  1)ed  of  a  small  creek 
at  F.  The  Clinton  bed  is  simi- 
larly traceable,  with  slight  in- 
terruption, to  D;  and  the  quart- 
zose sandstone  passes  under  the 
di'ift  at  ('.  Where  each  rock  ledge  is  last  seen  it  points  toward 
the  northwest,  and  betrays  no  tendency  to  curve  around  and 
join  its  fellow  in  the  opposite  wall.  In  the  intervening  sjjace 
the  side  of  the  gorge  seems  to  be  composed  entirely  of  di-ift. 
Sand  aud  clay,  pebbles  and  bowlders,  make  up  the  slope;  and  n 
beach  of  bowlders  margins  the  water  from  B  to  ('.  It  is  inferred 
from  this  arrangement  of  rock  and  drift  that  there  was  a  deep 
hollow  in  the  plain  before  the  drift  was  sjtread  by  the  ice,  the 
drift  being  depositeil  in  it  and  ovei-  it  until  it  was  filled  and 
covered.  The  parallel  directions  of  the  rock  leclnes  suggest  that 
the  hollow  was  part  of  a  stream  channel  running  northw(»stward  ; 
and  this  interpretation  is  borne  out  not  only  by  certain  topo- 
graphic features  two  or  three  miles  away,  but  by  a  study  of  the 
bed  and  banks  of  Bowman  Creek  (Fig.  15).  That  stream,  Avhich 
rises  two  miles  away,  has  carved  a  ravine  where  it  approaches 
the  Whirlpool.  The  noi-theast  bank  of  the  ravine  (Fig.  20)  seems 
to  be  composed  entirely  of  drift ;  but  the  opposite  bank,  th<mgh 
chiefly  of  drift,  lays  l)are  the  rock  at  a  numlu'r  of  places,  reveal- 
ing a  sloping  wall  descending  toward  the  northeast.  The  bed 
of  the  stream  in  general  shows  nothing  but  drift;  bnt  there  is 
one  place  where  the  creek  swerves  a  little  to  the  southward,  and 


'2o'2  NIA(i.U!.\    lALLS    AND   THEIl!    HISTORY. 

for  a  tVw  rods  presses  against  tlic  rock  slope;  and  il  lias  tlicre 
made  a  small  eiit  into  the  rock,  eascading  at  one  i)oiut  over  a 
sandy  ledge  that  is  harder  than  the  associated  shale. 

With  the  aid  of  this  information,  it  is  easy  to  understand  the 
peenliar  features  of  the  AVliiil]K)i>l.  The  Niagara  River  did  not 
seek  this  old  channel  and  thus  find  an  easy  Avay  northward,  liut 
ran  upon  it  ai-cideiitaily  at  one  jioint.  Its  course  on  the  jdain 
was  determined  for  it  hy  the  slojies  of  tlie  drift,  and  the  arrange- 
ment of  tliese  slopes  happened  to  guide  the  water  aci'oss  the 
liuried  channel  at  the  "Whirlpool.  Jn  making  the  gorge  from  the 
Whirlpool  to  the  escarpment,  and  also  in  making  tlie  u]ii)er  part 
of  the  gorge,  the  river  found  liard  rock  to  be  removed;  and  it 
worked  as  a  (puirr;^nuan,  diggiug  down  lielow  in  the  softer  rocks 
with  such  tools  as  it  had  to  use,  and  thus  xiuderniining  the  lime- 
stone cap.  At  tlie  Whirli:)ool  there  was  no  need  to  quarry,  be- 
cause there  was  no  limestone  cap;  and,  to  carry  cmt  the  homely 
figure,  the  river  merely  d\ig  in  a  gravel  pit,  shoveling  the  loose 
drift  (luickly  away.  This  work  of  excavation  did  not  cease 
when  a  channel  of  the  usual  Avidth  had  been  opened,  l)ecause  the 
angle  in  the  course  of  the  river  set  the  current  strongly  agaiust 
the  bank  ()f  drift,  and  caused  it  to  clear  out  a  liasin  in  the  old 
channel.  Had  the  drift  been  wholly,  as  it  is  partly,  of  sand,  still 
more  of  it  would  have  been  carried  out ;  but  it  included  large 
bowldei's,  and  these  were  sorted  oiit  and  acciunulated  mitil  tliey 
made  a  sloping  Avail  or  sheathing,  Avliich  covers  all  that  part  of 
the  sand  below  the  level  of  the  ]>ool,  and  I'esists  further  en<'roach- 
nient  by  the  water.  So  the  peculiar  form  of  the  river  at  this 
place  was  caused  by  the  old  channel  with  its  filling  of  loose  saud 
and  gravel.  The  looped  cun-ent  evidently  depends  on  the  pecul- 
iar shape  of  the  channel.  The  water  enters  the  pool  with  such 
impetus  that  it  is  carried  past  the  outlet,  and  the  retiirn  current 
follows  the  bottom  of  the  pool  because  that  route  is  the  easiest. 

TIME. 

Just  under  the  escarpment  where  it  is  divideil  by  the  river 
stand  two  villages,  —  the  American  village  of  Lewiston,  the 
Canadian  village  of  Queenstou.  Lewiston  is  built  partly  on  an 
old  beach  of  l>ake  Iroipiois,  and  near  its  steamboat  wharf  is  a 
gravel  pit  where  one  can  see  the  peVibles  that  Avere  Avorn  round 
by  rolling  up  and  down  the  old  strand.    That  part  of  the  escarj)- 


JIMK.  233 

nieut  wliicli  overlooks  Lewiston  is  somewhat  terraced,  or  divided 
into  steps,  aii<l  was  called  "The  Three  Mountains"  a  century 
aj^o,  when  loads  that  liad  l)i>eu  l>r()U,ii:lit  by  boat  to  tlie  landins; 
(Lewiston)  wt-i-e  toilsomely  carried  U[)  the  steep  ascent  on  their 
way  to  other  lioats  jTlying  ou  the  ui>per  Niagara. 

TheescarpiiK'nt  alioveQueenstoii  is  called (^ueenston  Heights; 
and  from  its  crest  rises  Brock's  monument,  a  slender  shaft  com- 
memorative of  a  battle  between  British  and  American  soldiers. 
Within  this  sliaft  is  a  spiral  staii-case,  and  from  a  little  chandjer 
near  tht>  top  one  can  look  through  portholes  far  away  in  all 
directions.  Eastward  and  westwaid  runs  the  escarjiment,  and 
the  eye  follows  it  for  many  miles.  Sonthwai'd  stretches  the 
ujiper  plain,  diversified  Ijy  low,  I'olling  hills,  and  divided  in  the 
foreground  by  the  gorge.  In  the  still  aii'  a  cloud  of  si)i'ay  hov- 
ers over  tlie  catai'act,  and  a  cloud  of  smoke  at  the  horizon  tells 
of  Buffalo.  Northward  lies  blue  Ontario,  and  straight  to  its 
shore  flows  the  deep-channeled,  majestic  Niagara,  dividing  the 
smooth  green  lowhunl  into  parts  even  more  closely  kin  than  the 
brother  nations  by  which  they  are  tilled.  Beyond  the  watei-,  and 
forty  miles  away,  gleams  Scarboro  Cliff,  where  the  lake  waves  are 
undermining  a  hill  of  di-ift ;  and  twenty  or  thirty  miles  farther 
the  imagination  may  supply — what  the  earth's  roundness  con- 
ceals from  the  eye — a  higher  ujtiand  that  Itounds  the  Ontai'io 
basin. 

The  Brock  monument,  the  Niagara  gorge,  and  the  Ontario 
l)asin  are  three  pi-oducts  of  human  or  of  natural  work,  so  related 
to  time  that  their  magnitudes  help  the  mind  in  gras})ing  the  time 
factor  in  Niagara  history.  The  monument,  measured  in  diameter 
by  feet  and  in  height  l)y  scores  of  feet,  stands  for  the  epoch  of 
the  white  man  in  America.  The  gorge,  measured  in  width  by 
hundreds  of  yards  and  in  length  by  miles,  stands  for  the  ejioch 
since  the  ice  age.  The  l)asin,  measured  in  width  by  scores  of 
miles  and  in  length  by  hundreds  of  miles,  stands  for  a  period  be- 
fore the  ice,  when  the  uplands  and  lowlands  of  the  region  Avere 
carved  fr<tni  a  still  greater  upland.  The  monument  is  half  a 
century  old;  the  gorge  was  begun  some  teTis  or  hundreds,  or 
possibly  thousands,  of  centuries  ago;  and  the  hollowing  of  the 
basin  consumed  a  time  so  far  lieyond  our  comprehension  that 
we  can  only  say  it  is  related  to  the  gorge  epoch  in  some  such  way 
as  the  gorge  epoch  is  related  to  the  monument's  half  eentury. 

The  glacier  made  <'hanges  in  the  Ontai-io  l)asin,  but  they  were 


lj;;4  NIAGARA    FALLS    AND   THEIU    HISTOKV. 

small  in  comparison  with  its  oiij^ual  size,  and  the  basin  is  chiefly 
the  work  of  other  agents.  Before  the  iilacial  aye  it  was  a  river 
valley,  and  we  may  obtain  some  idea  of  its  origin  l)y  thinking  of 
the  Niagara  gorge  as  the  beginning  of  a  river  valley,  and  trying 
to  imagine  its  mode  of  growing  broader.  It  has  aheady  been 
explained  (p.  218)  that  the  gorge  walls  fall  baek  a  little  after  the 
cataract  has  lle^^^l  them  out,  biit  seem  to  come  to  rest  as  soon  as 
all  the  shale  is  covered  by  talus.  So  nearly  do  they  approach 
rest  that  their  jjrofile  is  as  steep  near  the  mouth  of  the  gorge  as 
it  is  one  mile  below  the  cataract;  l)Ut,  in  fact,  they  are  not  un- 
changing. Water  trickling  over  the  limestone  cliff  dissolves  a 
uiiHutequantity  of  the  rock.  This  makes  it  porous,  and  lichens 
take  root.  Lichens  and  other  plants  add  something  to  the  water 
that  increases  its  solvent  jiower.  The  fragments  of  the  talus  are 
eaten  faster  becaxTse  they  expose  more  surface.  Each  winter  the 
frost  disturbs  some  of  the  stones  of  the  talus,  so  that  they  slowly 
move  down  the  slope;  and  wherever  the  shale  is  laid  bare,  frost 
and  rain  attack  it  again.  Thus,  with  almost  infinite  slowness, — 
so  slowly  that  the  entire  age  of  the  gorge  is  too  short  a  unit  for 
its  measurement, — the  walls  of  the  gorge  are  retreating  from  the 
i-iver.  At  the  same  time  every  creek  that  falls  into  the  gorge  is 
making  a  narrow  side  gorge.  The  strongest  of  them  has  worked 
back  oidy  a  few  hundred  feet  (Fig.  13);  but  in  time  they,  will 
trench  the  plain  in  many  directions,  and  each  trench  will  open 
two  walls  to  the  attack  of  the  elements.  Space  forbids  that  we 
trace  the  2>rocess  further;  Imt  enough  has  been  said  to  show 
that  valleys  are  made  far  more  slowly  than  gorges,  and  that  the 
ancient  shaping  of  the  land  into  valley  and  upland  was  a  far 
greater  task  than  the  comparatively  modern  digging  of  the 
gorge. 

The  middle  term  of  our  time  scale,  the  age  of  the  gorge,  has 
excited  great  interest,  because  the  visible  work  of  the  river  and 
the  ^■^sible  dimensions  of  the  gorge  seem  to  afford  a  means  of 
measuring  in  years  one  of  the  periods  of  which  geologic  time  is 
composed.  To  measure  the  age  of  the  river  is  to  detennine  the 
antiquity  of  the  close  of  the  ice  age.  The  }irincipal  data  for  the 
measurement  are  as  follows:  (1)  The  gorge  now  grows  longer  at 
the  rate  of  fom*  or  five  feet  a  year,  and  its  total  length  is  six  or 
seven  miles.  (2)  At  the  "\Miirlpool  the  rate  of  gorge  making 
was  relatively  very  fast,  because  only  loose  material  had  to  be 
removed.     Whether  the  old  channel  ended  at  the  "Whirlpool,  oi- 


TIME.  235 

extended  for  some  distance  southward  ou  the  line  of  the  river,  is 
a  matter  of  doubt.  (3)  Part  of  the  time  the  volume  of  the  river 
was  so  much  less  that  the  rate  of  recession  was  more  like  that  of 
the  American  Fall  than  that  of  the  Horseshoe.  Some  suggestions 
as  to  the  comj^arative  extent  of  slow  work  and  fast  work  are  to 
be  obtained  from  the  profile  of  the  bottom  of  the  gorge.  AVhile 
the  volume  of  the  river  was  large,  we  may  supjiose  tliat  it  dug 
deeply,  just  as  it  now  digs  under  the  Horseshoe  Fall  (see  p.  21G) ; 
while  the  volume  was  small,  we  may  suppose  that  a  deep  pool 


Fio.  21.  —  Longitudinal  Section  of  the  Niagara  Gorge,  with  Diagram  of  the 

Western  Wall. 

The  base  line  is  at  sea  levt'l.    It  is  flivirted  into  miles.    Wat^r,  black;  drift,  dotted;  Kint;ara 

limestone  in  block  pattein ;  shales,  lirokeii  lines;  !•",  falls;  I{,  r.iilway  bridges; 

W,  wbirlpool ;  Foster,  Foster  Flats;  E,  escarpment. 

was  not  made.  Fig.  21  exhibits  the  approximate  depth  of  the 
water  channel  through  the  length  of  the  gorge ;  and  liy  examin- 
ing it  the  reader  will  see  that  the  depth  is  great  neai-  the  mouth 
of  the  gorge,  again  from  the  head  of  Foster  Flats  to  the  Whirl- 
pool, and  then  from  the  bridges  to  the  Horseshoe  Fall.  It  is 
small,  indicating  slow  recession,  in  the  neighborhood  of  Foster 
Flats,  and  also  between  the  Wliirl})Ool  and  the  railroad  bridges. 
The  problem  is  complicated  by  other  factors,  but  they  are  prob- 
ably less  important  than  those  stated. 

Before  the  modern  rate  of  recession  had  been  determined, 
there  were  many  estimates  of  the  age  of  the  river;  but  their 
basis  of  fact  was  so  slender  that  they  were  hardly  more  than 
guesses.  The  first  estimate  with  a  better  foundation  was  made 
by  Dr.  Julius  Pohlman,  who  took  account  of  the  measured  rate 
of  recession  and  the  influence  of  the  old  channel  at  the  Whirl- 
pool ;  he  thought  the  river  not  older  than  3,500  years.  Dr.  J.  W. 
Spencer,  adding  to  these  factors  the  variations  in  the  river's 
volume,  computes  the  river's  age  as  32,000  years.  Mr.  Warren 
Upham,  having  the  same  facts  before  him,  thinks  7,000  j^ears  a 
more  reasonable  estimate.  And  Mr.  F.  B.  Taylor,  while  re- 
garding the  data  as  altogether  insufficient  for  the  solution  of 
the  problem,  is  of  opinion  that  Mr.  Upham's  estimate  sliould  be 
multiplied  by  a  number  consisting  of  tens  rather  than  units. 
Thus  estimates  founded  on  substantially  the  same  facts  range 


236  NIAGARA  FALLS  AND   THEIR  HISTOKY. 

from  thousands  of  years  to  hundreds  of  thousands  of  years. 
For  myself,  I  am  disposed  to  agi-ee  with  Mr.  Taylor,  that  no  es- 
timate yet  made  has  great  value,  and  the  best  result  obtainable 
may  perhaps  be  only  a  rough  approximation. 


BOOKS  OF  REFERENCE. 

Hall,  Basil,  R.N.     Forty  Etchings,  from  Sketches  made  with  the  Camera  Lucida  in 

North  America  in  1827  and  1828.     Edinburgh  and  London,  1829. 
H.\LL,  Jasies.      Niagara  Falls :  its  Past,  Pi-eseut,  and  R-ospective  Condition  (Nat. 

Hist,  of  New  York,  Geology,  Part  IV.).     Albany,  1843. 
Lyell,  Charles.     Travels  in  North  America.     London.  1845. 
Tyxdall,  John.     Some  Observations  on  Niagara  (Popular  Science  Monthly,  vol.  iii., 

1873). 
Pohlm.\k,  Julius.     The  Life-History  of  Niagara  (Trans.  Am.  Inst.  Mining  Engineers, 

1888). 
Gilbert,  G.  K.     The  History  of  the  Niagara  River  (Sixth  Ann.  Kept.  Commissioners 

State  Reservation  at  Niagara).     Albany,  1S90. 
KiBBE,  Arc.  S.     Report  of  the  Survey  to  determine  the  Crest  Lines  of  the  Falls  of 

Niagara  in   1890   (Seventh  Ann.   Rept.   Commissioners    State    Reservation    at 

Niagara).     Albany,  1891. 
Shaler,  N.  S.    The  Geology  of  Niagara  Falls  (The  Niagara  Book).     Buffalo,  1893. 
Spencer,  J.  W.     The  Duration  of  Niagara  Falls  (Am.  Jour.  Science,  3d  Series,  vol. 

xlviii.,  1894). 
Tatlor,  F.  B.     Niagara  and  the  Great  Lakes  (Am.  Jour.  Science,  3d  Series,  vol. 

xlix.,  1895). 


MOUNT  SHASTA,  A  TYPICAL  VOLCANO. 


By  J.  S.  DiLLER. 


THE     VOLCANIC    PKOCT.SS. 


Heeds  are  wafted  by  the  wind  to  fertile  soils,  where  they  ger- 
minate and  take  I'oot,  and  in  time  the  migiity  pine  becomes  the 
pride  of  the  forest ;  but  in  a  few  centuries  it  g!-ows  old,  declines, 
is  blown  over  by  tlie  winfi'r  st()rnis,  (h'cays,  and  returns  to  the 
soil  whence  it  came.  Animals,  little  at  l)irth,  grow  (o  full  stature 
and  maturity,  and  in  old  age  decline  and  pass  away. 

As  with  living  things,  so  also  with  the  glades  and  the  hills,  the 
valleys  and  the  mountains.  All  are  ever  changing  in  course 
either  of  construction  or  of  destruction,  or  of  both.  Each  has  its 
history  more  or  less  complete,  embracing  a  beginning  stage,  a 
stnge  of  maturity,  and  a  stage  of  d(>cadence. 

Mount  Shasta,  a  typical  large  volcano,  is  l)eyond  the  prime  of 
its  life.  It  is  in  the  decline  of  its  maturity.  It  has  passed  from 
a  stage  of  vigorous  growth  into  one  of  decadence,  and  is  just  be- 
ginning to  sliow  clearly  the  ravages  of  time.  In  order  to  prepare 
the  way  for  a  clearer  understanding  of  the  large  volcano,  it  will 
be  well  to  review  briefly  the  volcanic  i)rocess. 

There  ai-e  many  forces  active  in  changing  the  features  of  the 
earth's  surface.  As  explained  in  the  first  monograi)h,  three" 
ways  or  processes  in  which  these  foi'ces  operate  may  be  distin- 
guished.    They  are  riilcdi/isni,  (Viastnipli'isni,  and  i/rmldfidn. 

Vulcanism  (Monograph  No.  1,  j'.  -■+)  modifies  the  surface  by 
the  transfer  of  material,  generally  in  a  molten  eoudition,  outward 
from  the  earth's  interi<)r.  In  order  to  understand  this  transfei'  it 
is  necessary  to  consider  the  conditions  within  the  earth. 

Internal  Heat. —  In  a  boring  made  near  Wheeling,  W.  Va., 
the  temperatitre  at  various  depths  was  obsei'ved  as  follows:  at 
1,850  feet,  GS.TfjO  F. ;  2,125  feet,  7().25o ;  2,990  feet,  m.m° ;  3,482 

(Copyrigtit,  ISO.'i.  l>y  American  Book  ronijiany.) 
2.S7 


•2SS 


MOUNT   SHASTA,  A   TYPICAL  VOLCANO. 


feet,  93.60° ;  3,980  feet,  101.75° ;  4,402  feet,  110.15°.  The  teui- 
perature  thus  increased  downward  iit  the  rate  of  about  1  degi-ee 
for  every  75  feet.     Deep  borings,  wells,  ami  mines  at  many  points 

upon  the  earth's  surfaee  show  that 
everywhere  the  temperature  in- 
creases dowjiward  in  the  earth. 
Although  the  i-ate  varies  with  the 
place,  the  average  increase  is  about 
1  degree  for  every  45  to  75  feet. 
The  rate  of  increase  indicates  that 
at  a  depth  of  50  miles  beneath 
the  surface  the  temperature  is 
higher  than  tliat  reijuired  to  melt 
iron  under  ordinary  conditions. 
The  source  of  this  internal  heat, 
whether  a  residue  from  the  oiigi- 
nal  incandescent  earth,  or  due  to 
chemical  action,  or  produced  by  the 
mechanical  crushing  of  rocks,  we 
need  not  stop  to  inquii'e. 

"Water.  —  Rain  falls  on  tlie 
mountain  slopes.  Some  of  it 
gathers  into  rills,  runs  into  brooks, 
creeks,  and  rivers,  and  finally  finds 
its  way  back  into  the  sea  whence 
it  came.  Another  portion  enters 
the  soil,  and  undei-  the  influence  of 
gravity  passes  thi'ongh  the  poi-es, 
cracks,  and  fissures  of  the  rocks 
to  various  de]>tlis  within  the  earth. 
On  the  lower  slopes  of  the  mcmn- 
tains,  and  in  the  valleys,  much  of 
the  water  which  entered  above  re- 
appears in  the  form  of  springs, 
most  of  whicli  are  cool  and  refresh- 
ing. In  some  cases,  however,  the 
water  penetrates  so  far  into  the  earth  before  reappearing  in 
s}ti-ings  that  it  is  warmed  by  the  internal  lieat.  Thus  warm 
springs,  hot  springs,  and  boiling  springs  are  produced.  In  those 
l)oiling  s})rings  in  which  the  outlet  is  large  enougli  to  allow  the 
heat  to  escape,  the  movements  of  the  water  are  <'om])aratively 


Geyser  iu  Action. 


WAIKH.  231» 

uiiifonn ;  l)Ut  in  certaiti  cases  tlu;  outlet  is  narrow  in  jtroportion 
to  the  length  of  the  niore  or  less  vertical  tulie  in  the  groiUK.l,  ami 
tliere  is  not  sulHcient  opportunity  for  escape.  The  heat  increases 
until  the  expansive  force  of  the  liigiily  heated  water  an<l  steam 
is  sutticieut  to  produce  an  explosion.  The  overl>-iiig  water  and 
steam  are  thrown  high  into  the  air  (Fig.  1)  by  the  cniption.  Such 
springs  are   t/ri/scrs^  and   steam   is   the   motive  power  in  their 

CI'KptioJ/. 

The  waters  of  hot  sjirings  may  contain  in  solution  carliouate 
of  lime,  silica,  and  othei-  substances,  whicli  are  dei)osited  about 
the  springs,  making  a  mound.  The  one  fi-om  which  the  geyser, 
as  shown  in  Fig.  1,  issues  is  comjjosed  of  silica.  Although  .such 
mounds  rarely  attain  a  height  of  o\-er  '20  feet,  they  are  of  suffi- 
cient physiographic  importance  to  warrant  mention  here.  As  a 
class,  they  are  among  tlie  smallest  topographic  eminences  wliich 
are  products  of  a  process  essentially  volcanic,  in  its  nature. 

Next  more  important  than  eruptions  of  water  in  geysers  are 
those  of  mud.  A  notable  one  occnired  in  1S8H  at  Bandai-.san,  in 
Japan.  Large  quantities  of  mud,  saturated  willi  steam  or  higldy 
heated  water  under  pressure,  were  developed  a  sliort  distance 
beneath  the  surface.  A  great  exjjlosion  orcuri-iMl,  removing  the 
whole  side  of  the  mountain.  A  vast  (piantity  of  steam  escaped, 
and  streams  of  mud  flowed  down  the  valley,  damming  water 
courses  to  form  lakes,  and  destrojang  a  nund)er  of  \illages. 

In  true  voh-anic  action  the  material  transferred  from  tlie  in- 
terior of  tlie  earth  to  tlie  surface  is  neither  simple  water,  as  in 
the  geys(U',  nor  mud,  as  in  the  se?nivolcanic  eruption  at  Bandai- 
san,  but  melted  rock.  It  comes  from  greater  depths  tiian  either 
of  the  others,  where  the  tempei'ature  is  higher,  and  the  rocks 
either  in  a  molten  condition  or  so  hot  that  when  the  pi-essure 
u{)on  them  is  relieved  they  fuse  and  becoine  eiMii»tible. 

In  the  geyser  and  eruptions  of  mud  the  material  is  impelled 
to  tlie  surface  by  steam.  So  also  the  molten  rock  material,  or 
Diaf/Dia,  within  the  earth  is  forced  along  lines  of  least  resistance 
toward  the  surface  l)y  the  absorbeij  waters  ami  gases  it  contains. 
Other  agents  may,  indeed,  l>e  tlie  princi]>al  on(>s  in  causing 
the  upwelling  of  the  magma  frcnn  within  tlie  eartli ;  but  to  its 
absorbed  gases  are  due  many  of  the  conspicuous  phenomena 
attending  the  delivery  of  the  material  at  the  surface,  where  it 
solidifies,  and  becomes  lara.    The  large  qiiantities  of  .steam  given 


STATE  NORMALSCHOOL. 


L'40  MOUNT   SHASTA,  A   TYl'lCAL   VOLCANO. 

off  by  volcanoes  in  eruiitioii  arc  illustrated  iu  Fig.  l2  by  tlie-cloiuls 
of  vapor  rising  from  the  ontflow  of  lava  of  Vesuvius,  in  April, 
1872.  The  whole  mountain  is  involved  in  steam,  rising  from  the 
molten  rook  which  courses  dowji  its  slopes. 


Fig.  ". — Mount  Vesuvius  in   Eruiilimi,  April,  18712. 

Eruptions  Intekmittent. —  In  the  upbuilding  of  a  great  vol- 
cano like  IMount  Vesuvius  the  overflows  are  intermittent.  Erup- 
tions wliicli  transfer  molten  nintter  from  the  interior  to  the 
sui'faee  of  the  mountain  to  build  it  higher  are  not  continuous. 
The  brief  epochs  of  actixaty  are  ordinarily  separated  by  long 
periods  of  quiescence.  For  <'enturies  before  the  beginning  of 
the  Christian  era  Vesuvius  was  without  eruption;  but  in  the 
year  79  it  suddenly  burst  into  vigorous  action,  and  the  cities  of 
P()mj)eii,  Herculaneum,  and  Stable,  on  its  slopes,  were  over- 
whelmed and  destroyed  by  the  extruded  material.  Since  then 
it  has  been  in  erui)tion  many  times,  but  the  periods  occupied  by 
the  extrusion  of  the  molten  matter  have  been  very  short  as 
compared  with  the  long  intervals  of  repo.se. 

Forms  or  Eruption. — Erujjtions  are  of  two  forms, — explo- 
sive, emd  effusive.  In  the  first  form  the  material  is  blown  to  frag- 
ments and   violentlv  hurled   into   the  air.     In  the  second  the 


FORMS   OF  ERUPTION.  1241 

magma  wells  up  within  the  volcuuit-  vent,  and  flows  out  over 
the  surface  in  streams,  forming  cmdci'.s.  These  different  forms 
of  eruption  are  rarely  distinct.  Ordinarily  tliey  occur  togetlu^i- 
in  tlie  same  outburst,  and  the  mountain  1o  which  thej'  give  rise 
lias  a  complicated  structure. 

The  magma,  full  of  absoi-bed  gases,  Water,  or  steam,  distrib- 
uted tliroughout  its  mass,  or  perhaps  most  almndant  in  the 
upiiei-  2>oi'tion,  im^u'lled  l)y  foi-ees  not  yet  fully  understood,  rises 
toward  the  surface.  When  it  gets  near  the  surface,  and  the 
])ressure  is  relieved,  th(^  occhuh'd  gases  expand,  often  with  ex- 
plosive effect,  and  teai'  the  viscous  molten  material  into  fine 
particles,  which  are  hurled  high  into  the  air,  to  be  spread  far  and 
wide  over  the  land  l)y  the  winds.  During  tlie  gretit  ei'uption  of 
Krakatoa  in  August,  lS8o,  volcanic  dust  w.as  thi-own  to  tlie 
height  of  over  17  nnles,  and  the  surrounding  country  for  many 
miles  was  covered  with  a  sheet  of  volcanic  sand  and  dust. 

In  many-cases  the  ejected  fragments  are  coai'ser  than  dust, 
ranging  in  size  from  sand  tlii-ough  hipilli,  various  forms  of  cin- 
ders and  bombs,  to  blocks  of  lava  m;iny  tons  in  weight.  They 
fall  al)out  the  vent  from  which  the  material  is  ejected,  and,  pil- 
ing u]),  form  a  ciiidcr  couc.  Explosiv(>  eruptions  usually  accom- 
pany the  extrusion  of  viscous  lava.  Cinder  (>ones  generally 
have  steep  slopes,  and  funnel-slniped  craters  in  theii'  summits. 
They  are  abundant  along  the  Casciide  Iiangc*  in  the  western 
portions  of  the  great  volcanic  fields  of  California,  Oregon, 
Washington,  Idaho,  and  Montana. 

Magmas  containing  a  small  amount  of  absorlied  gases  and 
va{)ors,  or  having  such  a  high  degree  of  liquidity  as  to  allow 
the  gases  easily  to  escape,  are  not  extruded  by  exi)losive  erup- 
tions, but  are  quietly  jjoui-ed  out,  forming  in  each  case  a  laru 
couc  around  the  orifice.  Lic^uid  magmas  make  lava  cones  with 
gentle  slopes.  Cones  m;ide  from  viscous  magmas  have  stee]> 
slopes.  By  the  accumulated  outflows  of  li(iuid  niiigmas  for 
many  centuries,  high  mountains  are  built  up.  ]\Iauna  Loa,  on 
the  Island  of  Hawaii,  is  an  (»xample  of  such  a  mountain.  Its 
slo])es  are  gentle,  with  a,  base  .it  sea  level  70  miles  in  width,  and 
it  rises  to  a  height  of  aliout  14,000  feet  above  the  sea.  The 
amount  of  mat(>rial  poured  out  at  any  one  time  may  be  large  or 
small.  The  activitj'  is  always  intermittent,  with  relatively  long 
periods  of  quiet  sejjarating  short  intervals  of  ei'Ui>tion. 

As  lava   cones   and   cindei'  cones  are  built   u]i   higher  and 


J42  •  MOL'NT    SHASTA,  A    IVriCAL    VOLCANO. 

liigher  by  successive  eruptious,  the  passageway  or  chiimiey 
tliroiigli  wliich  the  material  comes  up  from  the  earth's  interior 
is  h^ugtheued,  ami  the  magma  lises  within  tlie  chimney.  The 
hydrostatic  pressure  of  tlie  cohimu  increases  as  it  rises,  until  it 
becomes  sufficient  to  l>urst  open  the  side  of  tlie  cone,  and  the 
lava  flows  out  on  the  lower  slopes. 

Volcanoes  arc  cinder  cones,  lava  cones,  or  cones  composed  of 
both  cinders  and  coulees.  They  are  conical  mountains  made  up 
wholly  of  volcanic  material  i)iled  up  around  the  vent  from  which 
it  issued.  Cinder  con»»s  and  lava  cones  are  common,  but  they 
are  usiuilly  less  imi>osin.u;  than  the  volcanoes  made  up  of  both 
cinders  and  coidet's,  such  as  result  from  explosive  and  effusive 
erui)tions  combined.  From  what  is  known  of  the  distribution  of 
volcanic  material,  it  is  probable  that  much  more  of  it  has  reached 
the  surface  by  effusive  than  l)y  explosive  eruptions. 

MOrXT     SHASTA. 

Location. — Mount  Shasta  is  in  the  middle  portion  of  north- 
ern California,  near  the  head  waters  of  Sacramento  Kiver,  and 
belongs  to  the  Cascade  Range  of  mountains.  It  immediately 
adjoins  the  Klamath  Mountains  of  the  Coast  Range,  aud  stands 
in  line  with  the  axis  of  the  Sierra  Nevada.  In  simple  grandeur 
it  rises  high  above  its  rugged  neighbors  as  a  mighty  monarch 
among  giants.  The  gi-eat  altitude  of  its  snow-capped  summit 
makes  it  a  conspicuous  landmark  over  a  large  area,  and  has 
guided  many  a  pioneer  on  his  way  to  the  Pacific  coast.  Mount 
Whitney  rises  higher  above  the  sea  than  Mount  Shasta;  but  as 
Mount  Whitney  is  located  among  rival  i>eaks,  on  an  extensive 
elevated  platform,  its  individual  sui>remacy  is  not  conspicuous. 
On  the  other  hand,  Mount  Shasta  stands  alone  at  the  head  of 
Shasta  Valley,  and,  although  encom]iassed  by  high  ridges  and 
])eaks,  it  still  in-esents  an  imposing  individuality.  The  traveler, 
in  that  region,  when  he  oi)tains  a  general  view,  need  not  ask 
which  is  Shasta.  The  mouutaius  in  its  neighborhood,  though 
reaching  over  2,500  feet  higher  than  any  of  the  Appalacliians, 
only  serve  to  magnify  the  gi-andetir  of  Shasta,  as  its  massive 
(^one  towers  a  mile  above  them  all. 

Shape  and  Size.  —  Mount  Shasta  seen  from  the  east,  as 
shown  in  Fig.  .3,  is  a  simple  cone.  So  far  at  least  as  shape  is 
concerned,  it  is  a  tyjiieal  exami)le  of  a  large  volcano,  made  up 


COMPOSITION   AND    STKUCTURE. 


24;{ 


of  cinders  and  coulees  which  accumulated  aliout  the  volcanic 
chimney  from  which  they  issued.  No  other  type  of  mountain 
attains  such  a  beautiful,  graceful,  yet  simple  and  extensive 
stretch  of  slope  risiiji;:  into  the  sky.  Tlie  point  of  view  in  Fig.  3  is 
over  a  mile  above  the  sea.  The  summit,  in  its  summer  garb,  rises 
8,450  feet  above  us,  and  attains  an  altitude  of  14,350  feet.  The 
upper  3,000  feet  of  the  mountain,  where  cliflfs  are  most  abundant. 


FlQ.  3. — Mount   Sliasta   from   the  East. 


has  slopes  averaging  nearly  35  degrees.  Farther  down,  the  slopes 
gradually  decrease  in  angle  of  inclination  to  20  degrees,  15  de- 
grees, and  10  degrees ;  and  fiiiiilly,  about  tlie  bas(^  of  the  mountaiit, 
the  long,  gentle  sloi)e  devdates  but  5  degrees  from  a  level  i)laiu. 
From  the  sunmiit  of  IMount  Shasta  toward  all  points  seen  in 
the  view,  its  flanks  increase  in  length  as  they  decrease  in  angle 
of  inclination.  Tlie  slope  of  the  mountain  as  a  whole  is  a  curve 
concave  ui)ward,  with  the  greatest  curvature  near  the  top. 

The  base  of  the  mountain  is  17  miles  in  diameter,  and  its 
height  above  the  base  is  over  2  miles.  Its  volume  is  in  the 
neighborhood  of  84  cubic  miles. 

Composition  and  Stuuctuue. — The  form  of  Mount  Shasta  is 
that  of  a  typical  volcano,  and  we  might  regard  the  form  alone  as 


244  MOUNT   SHASTA,  A   TYPICAL   VOLCANO. 

siiflScient  evideuce  to  prove  the  voleauk-  origin  of  the  mountain. 
There  are  other  facts  which  lead  to  the  same  conclusion. 

Volcanoes  art>  composed  of  rocks  which  result  from  the  cool- 
inj?  and  solidification  of  molten  material  erupted  from  the  inte- 
rior of  the  earth.  Jf  the  material  cools  slowly,  crystals  develop; 
and  the  amount  of  matter  ciystallized  is  proportional  to  the 
length  of  time  the  slow  cooling  continues.  In  some  cases  the 
process  is  continued  long  enough  for  the  whole  mass  to  becom«> 
crystallized.  (Tenerally,  however,  a  portii)n  of  the  material  in 
lavas  is  not  crystallized;  i.e.,  it  remains  amori)hous,  and  some- 
times even  glassy,  because  of  the  sud<lcn  chill  terminating  the 
gradual  cooling  before  crystallization  is  complete.  The  structure 
of  lavas  (made  uj>,  as  they  are,  of  either  crystals  or  amorphous 
material,  or  both)  is  peculiar,  and  affords  a  means  of  distinguish- 
ing volcanic  rocks  from  rocks  which  tn-iginate  in  other  ways. 

The  rocks  of  Mount  Shasta  usually  contain  some  well- 
developed  crystals,  l)ut  a  large  portion  of  the  mass  is  amori)hous. 
In  all  cases,  however,  their  structure  is  that  which  is  j)cculiar  to 
lavas,  and  there  can  be  no  doubt  as  to  the  origin  of  the  rocks. 


1  1'.-  4.  —  .Muuiil   .Siia.-Ia   troui   Iliv   .\uitli. 


COULEES.  245 

The  volcanic  origin  of  Mount  Shasta  is  iudicateil  uot  only  by 
its  form  and  composition,  hut  also  l)y  its  structure.  It  is  made 
up  of  irreguhu-  layers  of  lava,  altcrnatinfr  here  and  there  with 
others  of  fraixnieutal  volcanic  material.  The  layers  overhij)  one 
another  somewhat  lik(^  the  shingles  of  a  conical  roof,  and  piodvice 
the  structure  which  is  chai'actei-istic  of  volcanoes. 

CoNSTitrcTiONA].  Featikes.  —  Fi-om  1  he  east,  as  seen  in  Fig. ;!, 
Mount  Shasta  appears  to  ])e  a  single  cone,  as  if  all  the  lavas  of 
which  it  is  composed  luid  escajici!  iVom  one  vent.  Seen  from 
the  north,  as  illustrated  in  Fig.  4,  its  doubh'  strnctui-e  api)ears. 
\/  There  were  two  important  vents  about  a  mile  and  a  half  aj)art. 
The  principal  summit  is  on  the  left,  'i'hat  on  tlie  I'ight  is  Slias- 
tinn,  whose  altitude  is  about  2,000  feet  lower  than  the  other.  Its 
truncated  form  suggests  a  crater  in  the  smmnit ;  and  this  sug- 
gestion is  vei'ihed  by  ascent,  as  shown  in  tlie  map  (j).  L'-lCi).  The 
crater-like  rim  is  well  preserved,  except  on  the  west,  where  it  is 
broken  away.  On  the  slopes,  especially  towai-d  the  liase,  are 
a  nmnlier  of  smaller  cones.  Some  are  of  cinders,  and  others 
of  lava,  but  the  most  conuncui  fonri  of  ad<lition  in  l)uilding  uj) 
Mount  Shasta  was  coulees  without  cones. 

Coulees. — On  the  northwestern  sjojie,  at  an  altitude  of  from 
5,000  to  (),()()()  feet,  is  Lava  Park.  Judging  from  the  freshness  of 
tlie  lava,  it  is  the  youngest  coulee  of  the  mountain.  The  slope 
at  that  point  is  c(miparatively  gentle,  so  that  the  lava  sjtread 
broadly,  and  tlie  coulei^  is  nearly  as  wide  as  long.  The  greater 
portion  of  the  park  is  without  vegetation.  It  is  an  extremi'ly 
rough  jtile  of  rocks,  covei-ing  an  area  of  about  two  s(|uai('  miles, 
on  which  tliere  is  so  little  soil  that  arl)oreal  vegetation  has  not 
yet  obtained  a  hold.  It  ends  on  all  sides  aliruptly,  like  a  terrace. 
The  magma  was  viscous  at  the  time  of  its  extrusion,  and  l)roke 
into  sharp,  angular  blocks  as  it  was  ])nshed  along  over  the  sur- 
face. The  general  character  of  this  coulee  is  nuu-li  like  that 
shown  in  Fig.  .5,  which  rej)resents  a  coulee  on  the  little  Snag 
Lake  cinder  cone,  5S  miles  southeast  of  Blount  Shasta.  This 
form  of  coulee  is  exce])ti<)iial  on  the  slopes  of  ]\[(nuit  Shasta. 

A  well-marked  coulee  occurs  on  the  western  slope.  It  inir.st 
forth  at  an  elevation  of  5,000  f(>et,  and  flowed  northwestward  in 
a  rather  narrow  stream  for  several  miles.  'IMie  siii'face  of  this 
flow-  is  like  that  of  Lava  Park. 

A  com]»aratively  recent  coulee  appears  uii  the  southwestern 
slo{»e  of  the  mountain.     The  trail  u])  the  mountain  follows  lliis 


S«r*«T*4  frrUSCMtDfu)  i*rr*t'*»*-  E«CM<«iUaMcW  T<«»(f««k«r 


"«-  re*d»  ahoitt  &<>»M>i  farftukaJ  bv  C«Brf>  N.Nch 


MAP  OF  MOUNT  SHASTA. 


246 


COULEES. 


241 


••oule.  tor  several  ,n,Ies;  ai.d  the  rou^^h,  hackly,  stea,n-t..rn  sur- 
face of  the  ava  is  well  exposed.  It  is  timbered  like  the  a<lioin- 
mg  slopes,  showing  that  the  flow  is  older  than  ,Mtl,er  of  the  other 
two  mentione.1.     Its  surface  has  not  been  scored  by  the  ancient 


IffiMK  ,%^>  .'Trl'yfij 


Flc.  5.  —  T)u"  Surface  of  a   (  ..ul,,- 


li    Snag  Lake  (inili-r  ('(.n,-. 


gliic.iers  which  once  covered  a  large  i)art,  if  not  the  whole,  of  the 
southwestern  slope  of  the  mountain.  It  is  evident  that  its  ex- 
trusion occuiTcd  since  the  period  of  greatest  glacial  extension,  the 
glacial  period. 

On  the  northeastern  slope  of  the  mountain,  at  an  clcvjition  of 


X 


248  MOUNT   SHASTA,  A   TYPICAL   VOLCANO. 

nearly  10,000  feet,  several  well-marked  coulees  have  their  source. 
Their  tabular  fonn  may  be  distiuguished  iu  Fig.  o  between  the 
snow  and  the  forest.  The  longest  forms  the  flat  divide  be- 
tween the  ui>i»er  [lortious  of  iirewcr  and  Ineonstanee  creeks,  and 
courses  down  tlie  mountain  slope  for  t)ver  four  miles.  Below,  it 
widens  out  and  rises  higher  and  higher  above  the  adjacent  sur- 
face. The  lower  cud  is  abrupt,  and  forni«  a  prominent  clili.  The 
top  is  Hat  from  side  to  side,  but  the  edges  of  the  flow  are  steep. 
At  the  head  oi'  Brewer  (^reek  is  a  short  tabular  coule(>  tenninat- 
ing  below  in  a  cliff,  but  the  cliflf  is  uot  so  high  as  that  which  ter- 
minates the  longer  coidee.  In  gcnei'al,  the  newer  flows,  foiTuing 
the  upper  portion  of  the  mountain,  arc  smaller  than  the  older 
ones  over  which  they  were  poured  (mt.  All  end  below  in  cliffs; 
so  that,  as  one  iisccnds  the  mountain,  here  and  there  he  mounts 
as  if  on  giant  stairs,  with  long  inclined  steps  (or  treads)  and  steep 
risers,  over  the  ends  of  the  successively  siiorter  lava  Hows. 

The  later  Hows  that  Ijurst  from  the  upper  portion  of  the 
mountain  were  more  viscous,  and  generally  less  copious,  than 
those  which  issued  from  the  base.  The  former  built  up  the 
steep  slopes,  while  the  latter  sjiread  out  the  gentler  slopes  below, 
and  occasionally  formed  extensive  Hats,  as  shown  in  the  fore- 
ground of  Fig.  4.  At  the  southeast  base  of  the  mountain,  Elk 
Flats  is  underlined  by  a  liasjiltic  lav.-i,  which  at  the  time  of  its 
extrusion  was  much  more  liquid  than  most  of  the  lavas  of  Mount 
Shasta.  It  doubtless  contained  large  quantities  of  steam  at  the 
time  of  its  ern])tion,  for  the  lava  is  full  of  si'ijall  cavities  (liubbles), 
due  to  the  expansion  of  the  gases  it  originally  contained. 

The  longest  coulee  from  Mi>unt  Shasta  is  one  Avhich  issued 
from  the  southern  slope  of  the  mountain  at  an  elevation  of  about 
r),r)()0  feet,  a  little  more  thau  a  mile  southwest  of  the  Wagon 
Camj).  The  j)lentcons  How  of  lava  s]ircad  from  a  cone  on  the 
crest  of  the  ridge,  sending  one  arm  of  llic  lirojid  roulee  toward 
Panther  Creek,  and  another  toward  the  Sacramento.  It  com- 
]>letcly  surrounded  Bear  Butte,  and  forced  Panther  ("reek  east- 
ward. It  flowed  between  tlie  hills  of  metamorphic  rocks  along 
Soda  and  S(|u,iw  creeks.  This  branch  of  the  great  coulee  ter- 
minated within  a  dozen  miles  of  its  source.  The  other  arm  of 
the  How  entered  the  canyon  of  Sacramento  ]\iver,  wliich  it  fol- 
low«'(l  for  nearly  .lO  miles.  The  magma  was  tliin.  and  it  (hndit- 
less  spread  with  considerable  rapidity.  Wherever  the  How  was 
inqieded.  bi'oad  lake-like  exiiansions  of  the  stream  weiv  formed. 


COULEES.  24!) 

This  occurred  at  miiiicroiis  points  aloiij:!^  tlie  river,  just  ahove  the 
narrow  portions  of  the  canyon.  Tlie  surfaces  of  the  ponded 
tracts  are  smooth,  and  the  interrupted  drainage  leads  to  the 
development  of  meadows.  Tlie  best  example  of  this  sort  in  the 
Shasta  region  is  on  S(iua\v'  Creek,  four  miles  Ix'low  Nabar.  In 
some  regions  meadows  (h'velojK'd  in  this  way  are  of  much  im- 
portance. This  is  esiiecially  true  in  the  Lassen  Peak  district, 
over  50  miles  southeast  of  ]\Iount  Shasta,  wliere  a  large  part  of 
the  agricultural  land  was  tluis  produced. 
\  Although  a  comparatively  late  flow,  the  extrusion  of  the 
coulee  which  followed  down  the  Sacramento  occurred  many 
centuries  ago.  This  we  are  able  to  roughly  estimate  from  the 
fact  that  the  river  has  not  only  removed  nearly  all  of  the  lava 
from  the  canyon,  l)ut  has  cut  tht^  canyon  moi-e  than  a  hundred 
fe(!t  deeper  into  the  solid  rocks  than  it  was  at  the  time  the  lava 
followed  its  course.  At  many  points  ahmg  the  river^  between 
r})per  Soda  Springs  and  the  tunnel  four  miles  below  the  Sacra- 
mento Kiver  bridge,  there  are  terraces  of  lava  clinging  to  the 
sides  of  the  canyon.  These  terraces  are  remnants  of  a  once  con- 
tinuous coulee  that  reached  to  a  point  .")()  miles  from  its  source. 

None  of  the  Shasta  coulees  already  m(>ntioned  have  been 
glaviated.  Tlu^  suifaces  of  the  tlows  retain  their  pristine  rough- 
ness, and  it  is  evident  that  tiiey  have  lieen  (^xtruded  sin<'e  the 
glacial  period. 

The  postglacial  coulees  form  only  a  thin  local  vi-neer  on  the 
mountain  slopes.  Most  of  the  erui)ted  lava  is  older,  and  shows 
traces  of  glacial  action.  The  great  coulee  which  cour.ses  down 
the  southeastern  slopi*  of  the  mountain,  and  ends  in  a  prominent 
('lift'  between  Mud  and  Scpiaw  creeks,  is  well  glaciated.  Its  sur- 
face at  many  points  is  either  rounded  and  striated,  or  covered  by 
glacial  moraines.  IVFount  Shasta  was  nearly  as  large  during  the 
glacial  ])eiMod  as  it  is  now.  Since  that  episode  it  has  gained  liut 
little  more  by  addition  of  new  lava  flows  than  it  has  lost  by 
degradation. 

Near  th(^  summit,  on  the  southwestern  slope  of  the  mountain, 
is  a  coulee  of  exceptional  charactei-.  It  is  composed  chiefly  of 
lapilli,  and  forms  tliR  so-called  re(l-and-l)lack  rock  with  which  the 
climber  on  th(>  usual  trail  u])  Mount  Shasta  becomes  familiar 
at  an  elevation  of  from  i:!,(](>()  to  U,0(H)  feet.  The  material  is 
wholly  fragmental,  and  is  the  result  of  the  last  eruption  from  tlie 
sunnnit  of  Shasta.    The  cinder-covered  .slope  of  this  coulee,  over 


1250  JRUNT    SHASTA,  A     I  VrRAl>    VULCA.Nii. 

wiiii-li  the  trail  aiiinoarlics  tlic  siiiiiiiiit,  lias  the  appearance  oi  a 
recent  eruption,  and  it  is  pussilile  thiit  the  last  real  volcaiiic 
aelivity  al)i>ut  Mount  Shasta  oecni'ied  at  this  ]»)int. 

A  variety  of  surt'aee  features  of  the  lava  tlows  are  illustrated 
by  these  coulees.  The  rough,  angular  blocks  of  Lava  Park, 
the  steam-torn,  hackly  surface  of  the  trail  flow,  the  ciiider-cov- 
ei-ed  slope  of  the  flow  near  the  summit  of  the  uiountain  above 
^IcCloud  (Jlacier,  aud  the  bubl)ly  and  ropy  surface  of  the  Elk 
Flat  coulee,  are  good  examples  of  the  various  types  of  lava  sur- 
face. At  the  last-named  locality  the  suiface  is  in  ]tlaces  covered 
with  low  domes,  as  if  there  were  great  Imbliles  beneath.  This 
featui-e  is  better  illustrated  by  one  of  the  <>ld(>r  lavas  near  Ash 
Creek,  at  an  e]e\'ation  of  between  (i,0()()  and  .'-!,()()0  feet,  where 
they  have  various  forms  rising  sometimes  to  a  height  of  1:2  f(»et, 
with  a  diameter  of  l-t  feet,  and  usually  with  well-marked  radial 
jointing.  The  protuberan<'e  from  the  upper  surface  of  the  lava 
flow  sometimes  rises  so  high  that  it  bends  over,  as  if  about  to 
fall  from  its  own  weight. 

On  the  southwestern  slope  of  ^lud  (.'reek  Canyon,  below  the 
Upper  Falls,  is  a  prominent  glaciated  clitt"  75  feet  in  height.  It 
is  Ijeautifully  liauded  with  gray  and  red.  The  bands  vary  from 
a  small  fra<-tion  of  an  inch  to  a  foot  in  thickness,  and  aredoul)t- 
less  piimary,  originating  at  the  time  the  lava  was  erui>te<l. 

Cones.  —  The  pressure  of  the  magma  within  the  jjrincipal 
vent  burst  open  the  side  of  the  mountain.  (Jeneraliy  the  molten 
material  flowed  out  in  a  gentle  stream,  Imt  ()c<*asionally  it  rose 
fcmntain-like,  and  resulted  in  the  fcjrniatioii  of  a  ];iva  cone.  On 
the  northeastern  slope  of  the  mountain,  near  tlie  lower  edge  of 
the  snow,  is  a  hill  composed  wholly  of  lava.  Its  form,  as  seen  in 
tlie(listant  view,  suggests  that  it  is  a  lava  cone  directly  over  the 
vent  from  which  f\\o  lava  issued. 

On  the  southern  slope,  as  shown  on  the  map  (\k  -4()),  ranging 
from  8,000  feet  down  to  nearly  4,000  feet,  is  a  series  of  five  cones 
arranged  in  a  curved  line  gently  convex  to  the  westward.  All 
these  hills  are  lava  cones  except  the  one  at  an  elevation  of  6,800 
feet.  Beai'  i^>ntte  is  a  fine  example  of  a  lava  cone,  and  its  foiTn 
leads  us  to  expect  to  find  a  crater  in  its  snnnnit.  This  expecta- 
tion, however,  is  not  well  founded.  The  most  conspicuous  eleva- 
tioTi  of  this  kind  about  Mount  .Shasta  is  Cone  Mountain,  near  the 
railroad  at  the  western  base.  It  rises  over  1?,000  feet  above  the 
surrounding  country,  ami  its  slopes  are  indim-d  at  an  angle  of 


CONES.  1251 

al)out  .'!.")  (lefijrees.  Cone  Muuutaiu  \v;is  iiaiiit'd  l)y  Prol'essor 
Wliitiiey  ill  18G5  on  account  of  its  fonu.  Altlioi]fi:h  its  steep 
slopes  are  formed  chiefly  of  angular  fragments,  they  are  not 
I'iiiders,  lapilli,  bombs,  or  blocks,  such  as  result  from  exi)losive 
erui)tioii.  The  solid  lava  since  its  extrusion,  or  perhaps  in  jjart 
at  that  time,  was  broken  to  pieces.  There  is  no  trace  of  a  crater 
in  its  summit,  nor  of  ejected  fragmeiital  material  on  its  flanks, 
to  indicate  that  the  formation  of  the  cone  was  to  any  degree  due 
to  explosive  action.  At  the  time  of  its  extrusion  the  lava  must 
have  been  very  viscous  to  l)uild  up  such  a  sharp  cone.  Had  it 
been  as  liquid  as  that  of  Elk  Flat,  it  would  have  spread  out  so  as 
to  form  a  plain,  instead  of  a  prominent  mountain  several  tiiousand 
feet  in  height. 

Of  the  cinder  cones  there  are  about  lialf  a  dozen  f)ii  the  slo))es 
of  Mount  Shasta;  l)ut  they  are,  as  a  ride,  less  consjiicuous  than 
the  lava  cones.  Their  location  may  be  seen  on  the  map  in  cases 
where  they  are  sufficiently  elevated  to  lie  marked  by  one  or  more 
contours.  On  the  western  slojje  of  Lava  Park  is  a  (binder  cone 
over  200  feet  high,  with  a  well-preserved  crater  in  its  summit. 
Black  Butte,  northeast  of  IMount  Shasta,  has  a  double  crater, 
with  a  very  low  rim  of  cinders.  Those  ejet^ted  from  the  crater 
are  dark,  and  consist  of  tiie  same  sort  of  lava  as  tliat  of  wliicii 
tiie  most  of  Black  Butte  is  composed.  It  is  especially  interest- 
ing to  find  s(uittered  over  the  rim,  and  witliin  tliis  crater,  frag- 
ments of  pumice  like  that  ejected  by  the  last  erujition  from  tiie 
summit  of  Mount  Shasta.  It  indicates  clearly  that  Shasta  lias 
been  in  eru])tion  since  the  twin  crater  of  Black  Butte  was  formed. 

Black  Butte  can  scarcely  be  considered  a  part  of  Mount 
Sliasta,  althougli  its  lavas,  as  well  as  those  of  Ash  Creek  liutte, 
have  contributed  to  the  u]ibuildingof  the  mountain's  base.  Ash 
('reek  Butte  is  a  cone  containing  both  lavas  and  cinders;  and, 
judging  from  the  amoi;nt  of  (>rosion  it  has  sutt'ered,  it  is  of 
greater  age  than  the  other  cones  al)out  jNlount  Shasta. 

One  of  the  most  interc^sting  cinder  cones  on  the  sloi)es  of 
Mount  Shasta  is  between  the  two  branches  of  Panther  Creek,  at 
an  elevation  of  (J,rtO()  feet.  It  is  a  low,  rounded  dome,  composed 
of  red  lapilli,  and  is  sometimes  called  Red  Hill.  The  summit 
has  a  regular  convex  curve,  without  the  slightest  sugg(>stion  of  a 
crater  to  mark  tlie  liole  from  which  the  material  was  blown  out. 
Lava  has  escajjcd  from  its  liase  on  both  sidi^s,  and  two  short 
coulees  course  down  the  adjacent  ravines. 


•?n> 


MOUNT   SHASTA,  A   TYPICAL   VOLCANO. 


The  origin  of  such  dome-shaped,  cvaterless  oiuder  eoues  is  a 
ijiatter  of  doubt ;  l)Ut  a  suggestion  that  they  are  due  to  glaeial 
action  on  an  ordinary  cinder  cone  is  found  in  the  fact  tliat  tliis 
hill,  instead  of  being  exactly  conical,  is  elli]>tical,  with  its  longest 
axis  parallel  to  the  slope  of  the  mountain.  This  \-iew  is  strength- 
ened l>y  observations  on  a  sinulai'  cone  on  tlie  slope  of  Mount 
Shasta,  about  a  mile  northwest  from  the  road  at  the  summit  in 
the  pass  between  Mount  Shasta  and  Black  Butte.  The  uus>nn- 
metrical  elliptical  hill  at  this  plaee  is  about  KM)  feet  high,  with 
one  slope  of  4t)  degrees  and  the  other  t)nly  20  degrees.  The  top  is 
irregular,  dome-shaped,  without  a  trace  of  a  <lepression  or  crater 
to  mark  the  point  of  ejection.  On  the  sunnnit  are  a  number  of 
large  bowlders  of  lava,  <liffering  from  that  of  Avhich  the  hill  is 
composed.  They  must  have  been  carried  there,  and  the  most 
probable  agent  of  transportation  is  glacial  ice.  The  effect  of 
glacial  erosion  on  a  cinder  cone  over  which  it  passes,  if  not  too 
h»ng  continued,  so  as  to  remove  the  cone  entirely,  would  be  to 
oliliterate  the  crater,  and  make  a  more  or  less  elli]»tical  hill,  with 
its  longest  axis  parallel  to  glacial  motion.  The  two  elliptical 
cinder  cones  referred  to  are  preglacial:  while  the  others,  liaving 
well-preserved  craters,  are  postglacial. 

Southwest  of  Wagon  Camp  is  the  cinder  cone  from  wliose 
base  escaped  the  great  coulee  that  extends  down  tlie  S.-icramento 
Canyon  for  50  nules.  It  is  nearly  (iOO  feet  high,  with  well-detined 
crater,  suiTounded  by  a  rim  of  cinders.  This  is  one  of  the  most 
accessible  cinder  cones  on  the  mountain. 

Although  the  great  body  of  Mount  Shasta  is  made  up  of 
coulees  of  lava,  it  still  contains  a  large  proportion  of  fragmental 
material,  and  must  be  considered  a  mixed  cone.  On  the  north 
side  of  the  canyon  of  Mud  Creek,  at  an  elevation  of  from  8,000 
to  !),000  feet,  and  also  bek)w  the  timber  line  in  both  walls  of  the 
canyon,  there  are  fine  exposm-es  of  fragmental  material  ejected 
from  the  jn'incipal  crater.  With  the  exception  of  the  cinder 
coulee  already  noted,  this  is  the  most  important  exposure  of 
fragmental  material  ejected  from  the  main  vent. 

Mount  Shasta  is  a  doul)le  cone.  The  two  are  so  closely 
joined  as  to  make  but  one  cone  Ijelow  an  altittuh^  of  10,000  feet. 
AI)ove  this  k^ve!  the  two  cones  may  be  distinguished.  They 
mark  the  ininci]>al  vents  from  wliicli  Imrst  forth  the  coulees  to 
l)uild  uj)  the  great  mass  of  the  mounti)in.  All  the  other  cones 
on  the  slopes  of  tlie  jirincipal  one,  whether  composed  of  lava  or 


VARIETIES   OF   LAVA.  253 

cinders,  are  subordinate,  aud  make  the  position  of  subsidiary 
vents.  Besides  the  two  i)rineipal  vents,  there  are  traces  of  more 
than  a  score  of  subsidiaiy  ones  which  contributed  to  the  upltuild- 
ing  of  the  mass.  Many  others  may  be  found  covered  up  in  the 
gTowth  of  the  mountain  Ijy  the  coulees  coming  down  from  the 
principal  vents. 

Vakieties  of  Lava. — Rocks  resulting  from  the  solidification 
of  molten  material  brought  from  the  earth's  interior  by  volcanic 
action  are  volcanic  I'ocks.  There  arc;  many  varieties  of  volcanic 
rocks,  arising  fnjni  ditt'erences  in  structure  and  composition. 
Only  three  need  Ije  mentioned  here.  They  are  rhi/nHtc,  andesile, 
and  basalt,  and  their  distinction  is  based  largely  on  chemical  and 
mineralogic  composition.  Khyolites  contain  in  general  some- 
where l)etween  66  and  80  per  cent  of  silica;  andesites,  lietweeii 
55  and  &y  per  cent;  and  basalts,  between  45  and  55  pei-  cent. 
Silica  in  a  pure  state  is  illustrated  by  the  mineral  (piartz.  It  is 
a  substance  Avliich  is  fused  with  great  ditticully;  and  we  may  at 
once  infer  that  rhyolites,  being  more  siliceous  than  andesites 
and  basalts,  are  less  fusible.  On  this  acccmnt  rhyolites  at  the 
time  of  their  eruption  are  generally  much  more  viscous  aud  stiff 
than  basalts.  The  magmas  of  many  basalts  when  erupted  are 
almost  as  licpiid  as  water.  They  spread  far  and  wide  in  thin 
sheets,  with  even,  level  surface,  like  the  water  of  a  lake.  The 
degree  of  li(piidity  of  a  magma  at  the  time  of  its  eru2)tion  deter- 
mines the  shape  of  the  physiograi)hic  feature  to  which  it  gives  ri.se. 

The  lavas  of  Mount  Shasta  are  andesites  and  basalts.  Al- 
though intermingled  on  the  same  slope,  they  are  of  more  or  less 
distinct  eru^jtion,  and  associated  in  certain  cases  with  special 
topograi)hical  features.  The  most  ancient  variety  of  lava  about 
Mount  Shasta  is  one  contaijiing  prominent  crystals  of  black 
hornblende.  The  genei-al  color  of  the  rock  is  light  gray,  and, 
on  account  of  the  conspicuous  crystals  of  hornblende  it  contains, 
it  is  called  hoi-nblende  andesite.  It  is  <'xeniplified  in  Cone 
Mountain.  At  tli<'  time  of  its  ei-ui)tion  the  magma  was  evidently 
quite  viscous,  so  as  to  maintain  stee])  slo])es.  On  expo.smv  to  the 
weather  it  sometimes  becomes  reddish.  It  forms  a  large  tract  of 
the  westcM'u  slope  of  Shastina,  and  is  exposed  also  near  the  foot 
of  MeOloud  Glacier  and  other  localities  on  the  eastern  and 
northern  slopes. 

The  most  abundant  lava  of  Mount  Shasta  is  liy])erstliene 
andesite, —  a  lava  containing  little  or  no  hornblende,  Init  much 


254  MOUNT   SHASTA,  A   TYPICAL   VOLCANO. 

hypersthene.  It  rauges  in  color  t'loiu  light  and  dark  gray,  often 
reddish,  to  black.  This  entire  range  of  color  may  be  seen  on 
ascending  the  trail  uji  the  southwestern  slo^^e  of  the  mountain. 
The  trail  is  on  hj'persthene  andesite  all  the  way.  In  the  later 
stages  of  growth,  hyi>erstheue  andesite  has  contributed  nuich 
more  than  hornblende  andesite  to  tlic  upbuilding  of  the  mountain. 

The  third  variety,  basalt,  is  found  only  on  the  lower  slopes 
of  the  mountain,  forming  nearly  all  of  the  cinder  cones  and  the 
plains.  In  the  cinder  cones  the  lapilli  of  basalt  are  often  deeply 
colored,  red,  yellow,  or  black.  On  the  plains  the  basalt  is  gener- 
ally gray,  but  sometimes  verges  upon  black.  It  was  xisually  more 
liquid  at  the  time  of  its  eruption  than  t'ither  of  the  andesites, 
and  spread  out,  foi-niing  comparatively  smooth  surfaces,  as  at  Elk 
Flat  and  the  northern  foot  of  Mount  Shasta,  west  of  Sheep  Rock. 
If  all  the  lavas  that  now  appear  on  Mount  Shasta  had  been  as 
liquid  as  that  of  Elk  Flat,  the  form  of  Mount  Shasta  would  have 
been  very  different  from  that  which  it  now  has.  Of  this  w(» 
can  get  a  clearer  idea  by  comiiariug  ]\Iount  Shasta  with  Mauna 
Loa.  Mauna  Loa  is  14,000  feet  in  height.  Its  lavas  have  such 
a  high  degree  of  liquidity,  and  retain  their  mobility  so  long  after 
eruption,  that  the  base  of  the  mountain  spread  by  them  has  a 
diameter  of  about  70  miles  and  an  average  slope  of  .">  degrees. 
The  base  of  Mount  Shasta  is  less  than  "JO  miles  in  diameter,  and 
its  average  slope  nearly  15  degi'ees.  Eighteen  hundred  feet  below 
the  summit  of  ^Mauna  Loa  its  diameter  eqi;als  that  of  the  base  of 
Mount  Shasta,  while  the  diameter  of  the  latter  in  a  (torrespond- 
ing  jiosition  is  less  than  2  miles.  The  unlike  form  of  the  two 
mountains  is  attributable  chiefly  to  a  difference  in  the  degree  of 
li(inidity  of  the  lavas  of  which  they  were  constructed. 

Lava  Caves. —  In  the  gentle  lava  .slopes  about  two  miles 
southwest  of  Sheep  Rock  is  Plutos  Cave.  It  is  shaped  like 
a  railroad  tunnel.  The  l)ottom  is  generally  flat,  and  covered  by 
debris  fallen  from  the  sides  an<l  roof.  In  places  the  cave  is 
nearly  filled  with  such  material.  The  walls  ha\'e  a  sheUy  struc- 
ture, and  generally  form  a  beautiful  arch  across  the  cave.  An 
oi)ening  to  the  surface,  affording  an  entrance  to  the  subteiranean 
passage,  resulted  from  the  falling-in  of  the  roof.  The  cave, 
where  best  developed,  is  from  GO  to  80  feet  in  height,  and  from 
20  to  70  feet  in  width.  It  has  been  followed  for  nearly  a  mile 
without  finding  its  terjnination,  and  it  may  l)e  considerably 
longer.     The  crust  or  roof  of  the  tunnel  ranges  from  10  to  75 


MKTEOKOLCXiUAl.    (  (IXIHTIONS.  25.') 

feet  iu  thickness,  and  the  lava  of  whieii  it  is  composed  is  full  of 
cavities  fonueil  by  the  expaiidiug  steam  in  the  lava  at  the  time 
of  its  eruption.  Many  of  these  cavities  are  elongated  parallel 
to  the  tunnel ;  that  is,  in  the  direction  of  the  flow  of  the  lava. 

The  sides  and  roof  of  the  tunnel  have  caved  in,  so  that  the 
original  lining  of  the  cave  has  generally  disappeared;  but  rem- 
nants here  and  tliere  show  that  its  surface  was  spongy,  or  niai-ked 
by  narrow,  puckering  folds.  It  is  evident  that  tlie  cave  resulted 
from  the  escape  of  the  molten  inleiior  of  a  coulee.  The  crust 
formed;  but,  before  the  whole  mass  was  solid,  the  liquid  escaped 
farther  down  the  slo2)e,  and  flowed  out,  leaving  a  cavity  within 
the  coulee's  crust.  The  tunnel  is  liued  here  and  there  by  blisters 
and  froth-like  exudations  of  lava  from  the  sides;  but  no  distinct 
stala(^tites  and  stcilagmites  of  lava,  such  as  Professor  Dana  re- 
ported from  tlie  lava  tunnels  (m  the  slojies  of  Mauna  I>oa,  were 
seen  in  Plutos  Cave. 

The  surface  of  the  coiuitiy  about  IMutos  Cave  is  flat,  but 
rough,  with  iri'egular  domes  and  blisters  of  lava.  Judging  from 
the  hollow  sound  one  hears  in  walking  or  riding  over  many  por- 
tions of  the  lava  about  the  base  of  Mount  Shasta,  it  is  probable 
that  there  are  numerous  caves  in  that  ivgion.  8uch  caverns  are 
known  to  exist  not  oidy  at  the  northwestern  l)ase,  but  also  at  the 
southeastern,  in  the  neighborhood  of  Elk  Flat.  This  feature  of 
vulcanism  is  especially  well  displayed  in  the  so-called  lava  l)eds 
.")()  miles  northeast  of  ]\Ionnt  Shasta,  where  the  Indians  undei- 
(.'aptaiu  Jack  so  long  successlully  defied  our  troojis.  i\Iany  of 
file  tunnels  hav(*  caved  in,  leaving  the  country  fi-aversed  liy  dee]i, 
rocky  canals,  such  as  to  render  it  almost  imj)assable  at  right 
angles  to  the  flows.  During  the  winter,  snow  drifts  into  the 
canals,  and  forms  sulKcieut  accumulation  of  ice  in  some  cases  to 
last  all  summer,  furnishing  a  scanty  supjily  of  wat(M"  in  a  region 
wliere  it  is  otherwise  scarce. 

Meteoiiologic.vl  Coxditions.  —  In  strong  couti-ast  with  the 
^cii'cumstances  attending  the  upbuilding  of  Mount  Shasta  when 
it  was  an  active  volcano,  belching  fortii  streams  of  fiery  lava,  are 
its  arctic  conditious  of  to-day,  with  its  summit  wrappe<l  iu  eternal 
snow.  It  has  long  been  the  field  whereon  was  fought  the  ])attle 
l)etween  the  elements  within  the  earth  and  those  above  it.  In 
the  early  days  the  forces  beneath  were  victorious,  an<l  built  up 
the  mountain  in  the  face  of  wind  and  weather;  but  gradually  the 
volcanic  energy  reached  its  climax,  declined,  and  jiassed  away. 


'2i)(i  MOUNT    SHASTA,  A     lYl'ICAL    VOLCANO. 

Tlie  loss  of  lu'iit  was  succeoiled  by  icy  cold,  wliicli  oiifiicd  i  In-  way 
to  more  vigorous,  unrcpcllcd  attack  of  those  destructive  aj-'eucies 
tluit  are  now  reversing  the  jirocess,  and  slowly  hut  surely  wear- 
ing the  mountain  away,  and  reducing  it  toward  a  general  level. 

On  the  slopes  of  Mount  Shasta,  between  its  base  and  its  sum- 
nut,  there  is  a  wide  range  in  meteorological  conditions,  deter- 
mined by  <litferences  of  altitude,  thus  dividing  the  mountain  into 
climatic  zones.  On  tlie  middle  slope  is  the  great  forest  belt; 
above  it,  encii'cling  the  top,  is  the  cold,  moist  zone;  and  at  the 
very  lowest  points  of  the  base  of  the  moiuitain,  in  Shasta  \'alley 
and  Elk  Flat,  there  is  a  warmer,  dry  zone. 

The  lower,  middle,  and  upper  zones  dilfer  widely  not  only  iu 
temperature,  i)recipitati(>n,  and  vegetation,  but  also  in  tli(»ir 
slopes  and  consequent  gradational  featui-es. 

Lower  Zone.  —  The  influence  of  temperature  on  precipitation, 
and  the  limits  which  it  tlirows  al)out  arboreal  vegetation,  are 
liere  most  forcibly  illustrated.  This  zone  is  not  continuous  about 
the  mountain.  It  is  fully  developed  only  at  the  northwestern 
and  southeastern  bases  of  the  mountain  in  Shasta  Valley  and 
Elk  Flat.  In  Shasta  Valley,  at  an  elevation  of  about  3,000  feet 
above  the  sea,  where  the  average  temperatur(>  is  high  as  com- 
pared with  that  upon  the  mountain  itself,  tlie  precipitation  is 
always  in  the  fonn  of  rain,  but  not  sufficient  in  quantity,  espe- 
cially on  account  of  its  unequal  distribution  througlioitt  the  year, 
to  support  more  than  a  scanty  growth  of  stunted  trees.  In  the 
autumn,  storm  clouds  gather  al)out  the  smnmit,  and  showers 
become  frecjuent,  spreading  over  the  hmd  in  copious  I'ains.  Jie- 
fore  the  spring,  eight  ninths  of  all  the  annual  rain  has  fallen, 
and  the  country  is  brilliant  with  living  green.  As  summer  ad- 
vances, the  refreshing  showers  disappear,  and  the  clottdless  sky 
affords  no  protection  from  the  burning  sun ;  the  bright  green 
fades  away,  and  the  earth  gi-adually  assumes  that  imiuviting, 
seared  aspect  which  pervades  all  nature  in  the  season  of  droitght. 

Middle  Zone.  —  On  the  middle  slojies  of  tiie  moiuitain,  by  the 
cooling  influence  of  altittide,  the  rainfall  is  gradually  increased, 
and  th(»  vegetation  is  luxuriant.  From  the  limits  of  this  zone, 
arboreal  vegetation  gradually  diminishes  in  stature  and  number 
toward  the  upper  and  lower  zones.  The  trees  are  almost  wliolly 
coniferous.  Among  nearly  a  score  of  species  the  sugar  pine  is 
monarch,  frequently  attaining  a  diameter  of  12  feet  and  a  height 
of  over  200  feet.    Farther  up  the  mountain  these  gradually  give 


METROKOLOdlCAL   CONDITIOXS.  J'j^ 

■wiiy  to  firs,  wliosf  tall,  f;ra('i't'iil  tonus  live  in  pcrfeot  kopjiinji  w  itli 
the  iiiaj<^stii'  iiioiuitaiii  hchiiid  tln'iii.  Their  black-aud-yellow 
s])(itt<'il  trunks  and  l)raiR'hos,  drapcil  lierf  and  there  in  loug 
jx'udent  moss,  pi't-scut  a  wcii'd,  almosl  dismal  aspect,  makinfi  a 
tit  promenade  for  the  mythieal  deities  supposed  by  theaborigiues 
to  inhabit  the  mountain.  To  assume  that  in  tlie  timber  belt  the 
slopes  of  th(»  mountains  are  everywhere  covered  with  majestic 
trees  would  certainly  be  wide  of  the  trath,  for  within  the  forests 
are  large  treeless  tracts  sometinjes  luuidreds  of  acres  in  extent. 
From  a  distance  these  gi-een,  velvety  acres  appear  to  be  very  in- 
viting i»astures,  and  present  the  most  desirable  path  of  ascent. 
A  closer  examination,  however,  discovers  to  the  ob.server,  that, 
iustead  of  grass,  these  green  fields  are  clothed  in  such  a  dense 
shrubbery  of  manzanita,  Ceiuiotlius,  and  othei'  bushy  plants, 
as  to  be  almost  impas.sable.  One  attempt  to  cross  a  i>atch  of 
chaparral,  oi-  "devil's  acre,"  as  it  is  sometimes  ap]iropriately 
called  in  Western  vernacular,  will  convince  tin'  traveler  that  his 
best  path  lies  in  the  forest. 

Uppi'v  Zone. — The  timber  gradually  diminishes  in  .stature  as 
it  ascends  the  mountain  from  an  altitude  of  7,000  feet  to  the  re- 
gion where  the  precijiitation  is  generally,  if  not  always,  in  a  solid 
form,  —  snow  in  winter,  and  sleet  in  .summer.  On  the  southwest- 
ern slope  the  forests  cease  abruptly  at  au  elevation  of  about  8,000 
feet,  but  upon  the  opposite  slope  they  diminisli  gradually  to  the 
i-egion  covered  by  glaciers.  The  tree  which  climbs  highest  is 
Fh/Ufi  ulhkunlis.  Its  stem  becomes  shorter  and  the  top  flattens 
as  one  ascends.  ,\t  an  elevation  of  about  9,000  feet  the  branches 
are  spread  on  the  ground,  so  that  not  infrequently  the  pedestrian 
finds  his  best  path  over  the  tree  tops.  Beyond  these,  on  the 
suowless  slopes,  are  found  only  scattered  blades  of  grass,  and  the 
welcome  little  Iliilsra,  the  edelweiss  of  our  Al])ine  regions,  witli 
its  bright  flowers  to  alleviate  the  arctic  desolation  of  the  place. 
The  red  and  yellow  lichens  cling  to  the  rocks,  and  the  tiny 
Protococciis  flourishes  in  the  snow;  .so  that  one  is  occasionally 
surprised,  on  looking  hack,  to  see  his  "bloody"  footjjrinfs. 

In  the  Alps,  between  the  zone  of  forests  and  the  snow,  are 
often  found  exten.sive  pastures,  where  the  herds  which  furnish 
milk  for  the  celebrated  Swiss  cheese  graze  during  the  milder 
.seasons  of  the  year.  In  northern  California  sinular  pastures  do 
not  occur  about  the  snow-capped  summits,  probably  on  account 
of  the  unequal  distribution  of  the  annual  rainfall. 


GLACIERS.  255) 

(jtLACIEKs. — (Treat  interest  uttucliess  to  the  j^laciers  of  the 
upper  portiou  of  Mouut  81ia.sta.  There  are  live  in  number,  and 
all  are  found  side  by  side,  fonuing  an  almost  continuous  covei*- 
ing  for  that  portion  of  the  mountain  at  an  altitude  of  about 
10,000  feet.  On  the  northwestern  slope  of  the  mountain  is  Whit- 
ney Glacier,  with  its  j^rominent  terminal  moraine;  to  the  east- 
ward is  Bulam  Glaciei',  with  a  large  pile  of  debris  at  its  lower 
end ;  next  comes  the  broad  Hotlum  Glacier,  and  then  the  Wintun. 
McOloud  Glaciei-,  which  is  the  smallest  of  the  group,  lies  on  the 
southeastern  side  of  the  mountain. 

Whitney  GUk'u'i  . — Wliitney  GUicier  is  more  like  those  of  the 
Alps  than  any  other  om^  of  the  group.  Its  snow  field  lies  on  the 
northwestern  slope  of  the  mountain,  from  whence  the  icy  mass, 
with  well-defined  limits,  moves  down  a  shallow  depression  be- 
tween Shasta  and  Shastina.  Its  width  varies  from  1,000  to 
1^,000  feet,  with  a  length  of  about  2,;^  miles,  reaching  from  the 
summit  of  the  mountain  down  to  an  altitude  of  9,500  feet  abo.ve 
the  sea.  It  is  but  little  more  than  a  decade  since  the  first 
glaciers  were  discovered  within  the  riiited  States;  and  the 
hirgest  of  th(^m,  about  the  culminating  point  of  the  Cascade 
Range,  would  jjcrluips  a])pear  Lillii>utian  besidi'  the  great  glaciei' 
of  the  Bernese  Oberland ;  and  yet  they  are  as  truly  glaciers.  In 
the  upper  portion  of  its  coiu'se,  passing  over  prominent  irregu- 
larities in  its  bed,  the  Whitney  Glacier  becomes  deei)ly  fractured, 
producing  the  extremely  jagged  surface  corresponding  to  ice 
falls  of  the  Alpine  glaciers.  Lowei-  down  the  crevasses  develop, 
as  shown  in  Fig.  6;  and  these,  with  the  great  fissure  which 
separates  the  glacier  from  the  steep  slopes  of  Sliastina,  attest 
the  motion  of  the  icy  mass.  They  freciuently  oi)en  and  become 
yawning  chasms,  reaching  100  feet  into  the  clear  green  ice  be- 
neath. N(^ar  its  middle,  on  the  eastern  margin,  Wliitney  (xlai^ier 
receives  contributions  of  sand,  gravel,  and  bowlders  from  the  j 
vertical  clift's  around  which  it  turns  to  move  in  a  more  northerly 
direction.  In  this  way  a  prominent  lateral  moraine  is  developed. 
From  the  very  steep  slopes  of  Shastina,  on  the  western  side,  the 
glacier  i-ec^eives  additions  in  the  form  of  avalanches.  Here  the 
snow  clings  to  the  rocky  b(^d  until  the  strain  resulting  from  its 
accumulation  is  great  enough  to  lireak  it  from  its  moorings,  and 
it  rushes  down  upon  the  glacier  below.  The  most  striking  fea- 
ture of  Whitney  Glacier,  and  that  which  is  of  the  greatest  interest 
from  a  geologic  point  of  view,  is  the  debris  (moraine)  it  brings 


2()0 


MOUNT   SHASTA,  A   TVPKAI.   VOLCANO. 


(lowu  tlio  inouiitaiii  and  piles  up,  making:;  a  largo  aci-umulutioii 
(terminal  moraine)  at  its  lower  end.  This  moraine  (seen  in  Fig.  7) 
jippears  to  be  fully  a  mile  in  length,  measured  down  the  slope  of 
the  mountain.  Its  apparent  lengtli  is  much  greater  than  the  real, 
however,  from  the  fact  that  the  glaeier  ice  extends  far  beneath 
the  covering  of  detritus.  It  is  so  huge  a  pile  of  light-colored 
debris,  just  above  the  timlier  line,  that  it  is  ))lainly  visible  from 


—  Muunt   Sliast:i  from  the  Nortli. 


afai'.  The  view  aliove  (Fig.  7)  shows  clearly  the  double  character 
of  tlie  mountain, — Shastina  on  the  right,  and  Shasta  on  the  left, 
with  the  Whitney  Glacier  between  them. 

In  comparing  tlie  morainal  material  about  jNfount  Shasta 
with  that  of  the  Alpine  glaciers,  a  feature  that  is  particularly 
noticeable  is  the  smallness  of  the  bowlders.  On  Alpine  glaciers 
bowlders  frequently  have  a  diameter  greater  than  10  feet,  Itut 
about  the  Whitney  and  other  glaciers  of  Mount  Shasta  they  are 
rarely  so  much  as  ;>  fe'et  in  diameter.  Tins  is  readily  ex]ilaiiied 
by  the  fact  that  the  glaciers  of  Mount  Shasta  do  not  move  in 
deep  valleys,  bounded  by  long,  steep  slopes,  with  many  high 
cliffs,  affording  an  o])])ortunity  for  the  formation  of  large  bowl- 
ders.   Although  Wliitni'v  (Tlaciei-  has  its  boundai-ies  more  clearh' 


OLACIEKb.  261 

(It'fiiK^d  than  any  of  tla-  other  g-laciers  about  .Mount  Shasta  l.y 
th(i  depression  in  wliich  it  moves,  tlie  valley  is  veiy  shallow,  and 
one  looks  in  vain  along  its  slope  for  tra<,'es  of  polished  rocks  like 
those  so  magnificently  dis])layed  in  the  Alpine  valleys.  Whitney 
(Jlacier  looks  young:  it  has  hardly  made  a  heginning  toward 
carving  out  a  valley  for  itself. 

Below  the  terminal  moraine  the  milky  water  of  Whitney 
Creek  wends  its  way  down  the  northern  slope,  y>hinges  over  a 
fall  hundreds  of  feet  high  into  a  deep  canyon,  and  near  tlu,'  base 
of  the  mountain  is  consumed  by  the  thirsty  air  and  earth. 

The  pi-esence  of  marginal  crevasses,  lateral  and  tei-minal 
moraines,  and  the  <-liaracteiistic  milky  stream  which  issues  from 
the  lower  end,  are  proofs  that  Whitney  Glacier  moves,  but  the 
rate  of  motion  has  not  been  definitely  measured.  The  stakes 
planted  in  July,  1884,  were  covei-ed  with  snow  ])eforo  the  party 
could  rea(?h  them  in  October,  and  thej^  have  since  disappeai-ed. 

liitlant  (T/ncicr. — On  tlie  northwestern  slope  of  the  mountain, 
to  the  left  of  Whitney  Glaci(M-,  as  seen  in  Fig.  7,  is  the  Bulam, 
dift'eriug  cliiefiy  in  that  it  is  contained  in  a  broachM',  less  definite 
valley,  and  forming  an  intermediate  step  toward  Hotlum  Glacier, 
which  is  one  of  the  most  imjiortant  and  i-emai'kable  of  the  grouj). 

Hotlitiii  Glacier.  —  Unlike  the  ordinary  glaciers,  Hotlum  has 
no  valley  in  which  it  is  confined,  but  lies  on  the  convex  siuface 
of  the  mountain.  Its  u])p('r  surface  is  convex  throughout  from 
side  to  side,  and  its  width  {l."J;>  miles)  is  almost  as  great  as  its 
length  {l.()2  miles).  At  several  places  the  surface  of  the  glaciei- 
is  ma(h'  very  rough  by  the  ine(iualities  of  its  bed.  This  is 
especially  trvie  of  the  southern  ]>ortion,  where  ])r(miinent  dijfs 
furnish  material  for  the  only  medial  moraine  discovered  on 
Mount  Shasta.  Throughout  the  greater  portion  of  its  expanse 
tlie  glacier  is  deeply  crevassed,  exjiosing  the  green  ice  occasion- 
ally to  the  dei)th  of  10(1  feet.  The  thickness  of  this  glacier  has 
been  overestimated.  In  reality,  instead  of  being  1,800  to  2,r)00 
feet  thick,  it  does  not  api)ear  where  greatest  to  be  more  than  a 
few  hundi-ed  feet,  for  at  a  nund»er  of  places  it  is  so  thin  that  its 
bed  is  exposed.  Its  terminal  moraine  is  a  huge  j)ile  neai'ly  half 
a  mile  in  width  measured  in  the  direction  of  glacial  motion,  and 
twice  as  long  measured  along  the  end  of  the  glacier. 

Whifnii  (rlucicr.  —  Next  south  of  llotlum  (Jlacier  is  Wintun, 
which  attains  a  length  of  over  two  miles,  and  ends  with  an 
nbrupt  front  of  ice  in  a  canyon.     In  this  respect  it  is  strongly 


'2&2  MOUNT   SHASTA,  A   TYPICAL   VOLCANO. 

contrasted  with  tho  utlier  glaciers  of  Mornit  Shasta.  There  is 
uo  well-marked  terminal  nu)raiue,  although  there  are  accumula- 
tions of  del)ris  on  the  northern  side  ne:ir  the  end.  The  detritus 
is  ai>pavently  swept  out  of  the  eanyou  l)y  Ash  Creek  as  fast  as  it 
is  brought  there  l>y  the  glacier,  aud  thus  tlie  accunuilation  of  a 
terminal  moraine  is  ]irevente(l. 

McCloiul  Gluciri.  —  On  the  southeastern  slope  of  Mount 
Sliasta,  at  the  head  of  a  large  canyou,  is  the  McCloud  Glacier. 
It  adjoins  the  Wiutun,  aud  is  the  smallest  glacier  of  the  group. 
Notwithstanding  its  diminutive  size,  its  crevasses  and  the  muddy 
stream  it  initiates  indicate  clearly  that  the  ice  mass  coutinues  to 
move.  The  amount  of  moraiual  material  upou  its  borders  is 
small,  and  yet,  of  all  the  glaciers  ahout  Mount  Shasta,  it  is  the 
oidy  oue  which  has  left  a  promiueut  record  of  iuiportant  changes. 
The  country  adjacent  to  the  southwestern  side  of  ]Mud  Creek 
Canyon  has  been  distinctly  glaciated,  so  as  to  leave  no  doubt 
that  McCloud  Glacier  was  once  very  much  larger  than  it  is  at 
the  present  time.  The  rocks  over  which  it  moved  were  deeply 
striated,  and  so  abraded  as  to  produce  the  smooth,  rounded  sur- 
face so  common  in  glaciated  regions.  At  the  time  of  its  greatest 
extension  the  ghicier  was  over  5  miles  iu  length,  and  occupied 
an  area  of  at  least  7  sciuare  miles,  being  twenty  times  its  present 
size.  Its  limit  is  outlined  at  several  ])laces  by  i>rominent 
terminal  moraines,  which  mark  stages  in  the  recession  of  the 
glacier.  The  thic^kness  of  the  glacier,  where  greatest,  was  proba- 
bly not  more  than  "JOO  feet ;  for  several  hills  within  the  glaciated 
area  were  not  covei-ed,  and  the  striated  surfaces  and  moraines  do 
not  extend  u]>  their  slopes  more  than  200  feet.  The  thickness  of 
the  glacier  is  completely  in  harmony  with  the  limited  extent  of 
its  erosion.  Althoiigh  the  rocks  are  distinctly  i)laned  off,  so  that 
the  low  knobs  and  edges  have  regularly  curved  outlines,  it  is 
esideut  that  a  great  thickness  has  not  been  removed  by  the  ice, 
and  that  the  period  of  ice  erosion  has  been  comparatively  brief. 
Dui-ing  the  lapse  of  time,  however,  there  have  been  climatic 
oscillations,  embracing  epochs  of  glacial  advance  and  recession. 

With  the  exception  of  ]\IcCloud  Glacier,  there  are  no  records 
upon  the  slopes  of  Shasta  that  any  of  the  existing  glaciers  were 
ever  very  much  larger  than  at  present. 

At  the  southwestern  foot  of  the  mountain,  near  the  railroad, 
there  is  a  large  ai'ea  covered  by  gla<-ial  moraine  in  the  form  of 
rounded  and  irregular  hills,  inclosing  many  small  basins,  above 


SPRINGS.  263 

which  they  rise  rarelj-  as  iiiu<'ii  as  oO  feet.  This  moraiue  is 
composed  of  the  older  lavas  of  that  portiou  of  Mount  Shasta, 
and  demonstrates  that  during  the  glacial  i)eriod  the  southwest- 
ern slope  of  the  mountain  had  an  iee  stream  10  miles  in  length, 
'{'he  glaciers  on  the  othei-  portions  of  the  mountain  must  then 
have  been  much  larger  thau  uow,  and  it  is  prol)able  that  their 
records  havt^  to  a  large  extent  hccTi  buried  Iteneath  later  eruptions. 

Si'iiiN(;s. — -Made  up,  as  it  is,  of  iml)ricated  coulees  and  f rag- 
mental  material,  all  of  which  is  more  or  less  porous  and  full 
of  fissures.  Mount  Shasta  absorbs  the  principal  jioi'tion  of  the 
precipitation  on  its  slopes.  The  rainfall  on  Mount  Shasta  is 
large.  The  amount  of  water  that  reaches  McCloud,  Sacramento, 
and  Shasta  rivers  by  surface  drainage  is  very  small.  By  far  the 
greater  portion  of  the  drainage  of  Mount  Shasta  is  subterranc^an. 
This  is  shown  by  tht^  large  springs  aljout  its  base. 

The  Big  Spring,  above  Sissous,  is  a  fine  example,  giving  rise 
to  a  good-sized  stream,  that  by  sonu*  has  l)een  considered  the 
head  of  the  Sacramento.  Moss  Brae  Falls  are  produced  by 
springs  issuing  from  between  the  coulees  of  Mount  Shasta  on 
the  side  of  the  i^anyon  of  the  Sacramento,  and  cascading  ovei-  tlie 
grassy  slope  to  the  river  below. 

The  greatest  springs  are  those  in  McCloud  Canyon,  where 
the  river  cuts  the  southern  edge  of  the  lavas  from  Shasta  on  the 
border  of  Elk  Flat.  Large  volumes  of  water  issue  from  the  river 
bank,  and  the  size  of  the  sti'eam  is  (loid)led  by  their  addition. 

Scpiaw  Creek  originates  in  springs.  The  flow  is  copious, 
regular,  and  clear  as  crystal.  It  is  a  b(>autiful,  transj)arent, 
limpid  stream,  strongly  contrasted  with  its  nuiildy  neighl)or 
<'oming  down  from  McCloud  Glacier. 

Th(^  greatest  springs  are  low  down  the  mountain  sIojm',  al- 
though there  are  many  smaller  ones  above. 

On  the  summit  of  the  mountain  there  is  a  small  group  of 
openings  from  which  hot  sulphurous  gases  are  continuously  es- 
caping. The  place  is  sometimes  referred  to  as  the  Hot  Spring, 
but,  as  gases  only  escajie,  it  is  Tuore  propei'ly  called  a  sol/atani. 
The  earth  about  the  holes  is  warm,  but,  as  the  \'apoi's  are 
noxious,  the  pla<'e  cannot  b(>  used  as  a  source  of  heat  for  the 
camper  who  may  wish  to  remain  on  the  cold  summit  over  night. 
Down  the  northern  slope,  between  AVhitney  and  Bulam  glaciers, 
several  hundred  feet  below  the  summit,  is  another  solfatara. 
These  are  the  last  palpable  vestiges  of  heat  upon  the  mountain. 


21)4  MtUNT    SHASTA,  A    TVI'ICAI.    VoLCAXO. 

Stkeams.  —  A  <i:laiii'e  at  the  ma))  (\<.  -M'))  reveals  a  marked 
inegulavity  iu  the  distvibutiou  of  streams  on  the  slopes  of  Mount 
Shasta.  They  are  nearly  all  on  the  eastern  half  of  the  mountain, 
and  assoeiated  directly  witli  the  ,a;laciers.  The  reason  for  this 
distribution  is  found  in  the  iirevailinn-  soutlnvesterly  winds  of 
the  region.  These  are  so  strong  a)id  enduring  that  the  hrauehes 
of  the  exposed  trees  high  up  on  the  slopes  ai'e  l)lo\vn  around  to 
the  northeastern  side.  It  is  only  where  wiuds  continue  to  blow- 
steadily  for  a  long  time  in  one  direction  that  such  effects  can  be 
produced.  The  winter  storms  Avliich  furnish  the  Shasta  snow 
are  driven  by  such  winds,  and  the  snow  tin<ls  a  resting  place  only 
on  the  lee  side  of  the  mountain,  and  there  the  glaciers  are  formed. 

Though  all  the  streams  depend  for  tlieir  water  suiijily  upon 
the  snow  of  the  summit,  some  get  it  indirectly  through  springs, 
while  others  flow  directly  from  the  glaciers.  Squaw  Creek  has 
its  source  in  springs,  while  Miid  Creek  originates  in  McCloud 
Glacier.  Each  stream  is  a  good  example  of  its  kind.  They  are 
close  together,  and  yet  strongly  contrasted  iu  appearance. 
Squaw  Creek  is  a  beautiful,  clear,  refreshing  stream,  Avith  in- 
viting banks;  while  Mud  Ci-eek,  as  its  name  implies,  is  full  of 
sediment,  and  its  lianks  are  lined  witli  gravel,  sand,  and  mud. 
The  soiu'ce  of  the  detritus  is  the  glacier,  which,  as  it  gradually 
moves  down  the  mountain  slope,  armed  with  many  rock  frag- 
ments, files  ott'  the  surface,  and  jjroduces  the  mud,  sand,  and 
gravel  for  the  stream  to  carry  away.  Glacier  streams  vary 
greatly  in  vohime,  not  only  with  the  season,  but  also  with  the 
time  of  day.  I)i;ring  the  winter  there  is  little  melting  of  snow 
and  ice,  and  the  streams  have  little  water ;  l)ut  during  the  heated 
summer  the  supply  is  copious  and  floods  prevail.  For  the  same 
reason,  also,  the  stream  varies  between  day  and  night.  Thus  the 
returning  sxui  awakens  the  sleepy  sti'eam,  and  sends  the  thrill  of 
life  into  the  mountain's  circulation. 

Most  of  the  glacier  streams  sink  on  I'eaching  the  lower  slope 
of  the  mountain.  As  the  water  supply  declines,  the  point  at 
which  the  stream  disappears  in  its  bed  retreats  farther  up  the 
slope,  to  return  again  with  the  diurnal  pulsation  of  another  sun. 
In  the  long  streams  there  may  he  several  ])ulsations  at  the  same 
time.  The  hours  of  advance  and  retreat  of  the  stream  are  deter- 
mined chiefly  by  the  grade,  and  by  distance  from  the  glacier. 

Falls.  —  Tt  is  readily  understood  that  the  abrujit  termination 
of  the  coulees  below  leads  to  the  development  of  faUs  in  the 


DEGRADATIONAL  FEATUEES.  265 

.streiuus  which  find  tlieir  wiiy  down  the  mountain  slope.  All 
tlie  .streams  of  considerable  size  have  such  falls,  and  in  the  same 
stream  sevei-al  may  occur.  Mud  Creek  has  three, — one  within 
the  forest  Ijelt,  auotlier  near  the  timber  line,  and  a  third  more 
tliau  a  mile  farther  up  the  stream.  Ash  Creek  Fall,  near  the 
timl)er  line,  has  a  height  of  nearly  400  feet,  and  the  stream 
plunges  into  a  deep  canyon.  It  is  one  of  the  most  imi)ressive 
falls  of  the  mountain.  Bulam  Creek  and  Whitney  Creek  have 
similar  falls  of  great  height;  l)ut  the  streams  are  small,  and  on 
this  iicconnt  they  are  less  imitressive  than  those  of  Ash  Cre<'k. 

DE(ii!Ai)ATi()NAL  Featuues. —  \\V  huve  consideJ-ed  thost;  feii- 
tures  which  oi-iginate  in  the  upbuilding  of  the  mountain,  the 
meteorological  circiimst.inces  to  which  it  gave  birth,  the  forests, 
glaciers,  streams,  and  falls  that  followed.  Let  us  now  turn  our 
attention  to  the  degradational  featui'es  developed  by  these  con- 
ditions. The  three  zones  into  which  the  mountain  slope  is 
divided  by  its  meteorological  conditions  an\  well  marked  by  the 
consec^uent  degradational  featui'es.  Instead,  however,  of  desig- 
nating these  zones  according  to  elevation,  they  may  in  this  case 
be  named,  from  the  characterizing  featmv,  tlie  "Plain  Zone,"  the 
"Canyon  Zone,"  and  the  "Cirque  Zone"  respectively. 

Plain  Zone. — In  this  zone  fuUy  developed  plains  predominate, 
and  there  is  but  little  erosion.  Most  of  the  sti-eams  coming  down 
from  above  the  timber  line  sink  when  they  reach  the  plain  about 
the  base  of  the  mountain,  and  tlie  drainage  becomes  subterranean. 
Dotted  stream  lines  on  the  map  indic^ate  that  the  stream  beds  are 
usually  dry.  Whitney  Creek,  Inconstance  (^i-eek.  Brewer  Creek, 
Ash  Creek,  and  many  smaller  streams  disappear  from  the  sur- 
face during  a  large  part  of  the  year.  All  streams  are  enfeebled 
by  subterranean  leakage  by  the  time  they  reach  the  Plain  Zonc^, 
and  the  gentle  slopes  leave  them  little  power  of  corrasion. 

The  banks  of  the  glacier  streams  are  lined  with  gravel,  sand, 
and  mud  brought  down  from  above.  During  the  hot  season, 
when  the  floods  come;  from  the  melting  snows  of  the  upper  zone, 
the  streams  swell  far  beyond  their  winter  limits,  and  carry  away 
the  accunudated  debris.  The  low  grade  permits  the  streams  to 
do  l)ut  litth?  mor(^  than  this.  The  degradation  of  the  mouTitain's 
base  is  very  slow.  The  streams  flow  in  beds  near  the  general 
level,  and  degradational  features  are  not  conspicuous. 

Canjion  Zone. — The  Plain  Zone  passes  rather  abruptly  up- 
ward into  the  Canyon  Zone,  with  which  it  is  in  markcul  contrast. 


2(3(5  MOUNT   SHASTA,  A   TYPICAL   VOLCANO. 

The  Canyon  Zone  is  in  tlie  forest  belt.  The  protective  covering- 
of  Uviug  and  fallen  leaves  breaks  the  dash  of  the  raiu.  The  roots 
bind  the  soil  together,  and  the  shade  regulates  the  suddt'n 
changes  and  witle  range  of  temperatm-e.  Thus  the  forest  pro- 
tects the  slope  on  which  it  grows,  and  tends  to  prevent  rapid 
degradation.  This  difference,  however,*  does  not  modify  to  any 
considerable  extent  the  corrasion  of  the  tumultuous  streanjs 
fi-om  the  glaciers.  Hea^aly  armed  with  gravel  and  sand, 
tliey  act  upon  their  narrow  beds  somewliat  as  a  file,  continu- 
ally moving  down  the  slope,  and  cut  deep  canyons  across  the 
forest  belt. 

The  canyon  of  Mud  Creek  is  the  largest.  It  has  a  length  of 
al)out  5  miles,  and  a  depth  where  best  developed  of  about  1,000 
feet.  At  the  tindjei'  line  it  is  not  so  deep,  its  slopes  are  less 
precipitous,  and  the  canyon  is  crossed  by  n  rude  trail.  Else- 
where it  is  almost  impassable  for  horses.  The  middle  falls  of 
Mud  Creek  are  near  the  timber  line.  Above  this  point  the  south- 
west wall  of  the  canyon  is  made  up  largely  of  solid  coulees,  while 
the  opposite  side  is  comjjosed  chiefly  of  fragmental  material,  on 
whose  slopes  is  developed  the  pinnacled  tojiograi)hy  to  which 
such  formations  frequently  give  rise.  The  canyon  is  deepest  a 
mile  l)elow  the  timber  line.  Its  sides  have  a  slope  of  about  'M 
degrees,  with  occasional  columnar  cliffs  of  tufa,  reaching  in  some 
cases  a  heiglit  of  50  feet.  The  I'ocks  in  which  this  portion  of  the 
canyon  is  carved  are  almost  wholly  fraginciital.  It  is  treacherous 
climbing  ground,  for  the  rocks  arc  fragile,  and  afford  unreliable 
support.  They  are  more  or  less  distinctly  but  imperfectly  strati- 
fied, and  dij)  away  from  the  moitntain  at  an  angle  of  fi'om  8  to 
12  degrees.  The  slope  of  the  mountain  is  approximately  ]iarallel 
to  that  of  the  layers  of  fragmental  material,  and  suggests  that 
the  inclination  of  the  layers  was  determined  by  that  of  the  slope 
on  which  they  were  deposited,  (^oulees  of  lava,  where  observed, 
are  parallel  to  the  siim(>  slope,  and  it  is  apj)arent  tlint  some  of  the 
flows  followed  earlier  canyons  down  the  mountain  sk)i)e.  The 
three  falls  in  this  canyon  are  all  over  solid  coulees. 

The  canyon  of  Ash  (~^reek  is  neither  so  long  nor  so  deep  as 
that  of  Mud  Creek,  but  is  cut  in  harder  rocks.  It  ends  above  at 
the  falls,  where  the  stream  plunges  over  a  mass  of  lava  nearly 
400  feet  in  thickness.  The  canyon  walls  are  of  the  same  mate- 
rial near  the  falls;  Init  beyond,  the  cotilees  are  less  distinct,  and 
fragmental   mateiial    increases.     Two  miles   below   the  falls  a 


DEGKADATIONAX   FEATURES.  2()7 

stratum  of  pumiee  "JO  feet  thick  may  be  seen  lying  between 
somewhat  thicker  beds  of  saud  and  bowlders.  The  slopes,  al- 
tliough  steej),  aiv  generally  wooded,  and  landslides  are  less  fre- 
quent than  in  Mud  Creek  Canyon.  ^Striated  i-ocks  in  .situ  oceur 
near  the  bottom  of  the  canyon,  over  two  miles  below  the  present 
terminus  of  Wintun  Glacier. 

Brewer  and  luccmstance  creeks  are  small,  and  their  canyons 
are  of  corresponding  size.  On  the  other  hand,  Bulam  and  Wiiil- 
ney  creeks  are  laiger,  and  have  carved  canyons,  in  some  ])laees 
000  feet  deep,  down  the  northern  slojie  of  the  mountain. 

Cirque  Zone — The  Canyon  Zone  extends  up  the  sloj)e  of 
Mount  Shasta  to  an  elevation  of  uearly  10,000  feet.  At  the 
upper  ends  of  the  canyons  their  walls  n^treat,  and  the  valleys  , 
become  shallower,  and  spread  out  in  fan  shape,  forming  cirques 
against  the  mountain  summit.  The  glaciers  occupy  cii-ques. 
Those  of  McCloud,  Wintun,  and  Bulam  glaciers  are  the  best 
developed.  The  snow  slides  in  from  the  sides  and  head  of  the 
cirque,  and  the  corrasion  is  glacial.  At  lower  levels  the  snow 
and  ice  melt,  forming  streams  of  water  armed  with  glacial  gravel 
and  saud,  with  which  to  scour  their  beds  and  cut  the  canyons  of 
the  forest  belt.  The  circjues  are  wholly  abo\e  the  timber  line, 
and  are  of  glacial  oiigin.  The  divides  between  them  are  usuall>- 
sharp,  jagged  ridges,  whiles  in  the  Canyon  Zone  they  Jire  bi'oad 
and  even.  lu  this  last  ft^ature  (the  broad  and  even  divides)  is 
found  evidence  of  the  comparative  youth  of  Mount  Shasta,  its 
slopes  are  suiooth;  they  have  suffered^  but  little  from  general 
degradation  since  the  volcanic  forces  completed  its  construction. 
In  this  respect  it  is  strongly  contrasted  with  Mount  Kainier, 
which  has  been  deeply  sculptured  by  ice  and  water;  and  yet 
Mount  Rainier  is  less  tlian  halfway  in  the  course  of  eiosion  to- 
ward exposing  its  volcanic  ueck,  which  occupies  the  vent  thrt)Ugh 
which  the  lava  came  up  to  the  surface,  "^^^lile  the  early  stage  in 
the  degradation  of  volcanoes  does  not  differ  nuitt^'ially  from  that 
of  other  conical  mountains,  the  late  stage  in  which  the  volcanic 
neck  appears  is  peculiar  and  especially  chai'acteristic.  Thai 
iAlount  Shasta  has  a  great  core  of  solid  lava  in  its  center,  from 
which,  wIk^u  the  coulees  have  been  washed  away,  a  cons])icuous 
volcanic  neck  may  be  develojied,  there  can  be  no  doubt;  but,  if 
the  process  of  degradation  proceeds  as  now,  without  acceleration, 
it  will  be  many  centuries,  even  geologically  considered,  before 
the  neck  is  fully  brought  to  vieAv. 


•JliS  MOUNT   SHASTA,  A   TYPICAL    VOLCANO. 

AuE. — The  uphuildiu^  of  Mount  Shasta  is  but  a  matter  of 
yesterday  eouipaivd  with  tlie  lapse  of  ages  since  the  birth  of 
some  of  its  iieijjihliors.  The  (>oiiii)lex  gi'oup  of  mouutains  on  tlie 
west,  eml)raciug  S<'Ott,  Trinity,  Sahnon,  and  tSiskiyon,  all  of 
which  belong  to  the  Klamath  Mountains,  are  composed  in  large 
part  of  ancient  crystalline  i-ocks  of  both  aijUeous  and  igii(>ous 
origin.  Thi'ough  tliese  the  Klamath  and  the  Sacramento  rivers 
have  cut  deep  eauyous.  The  canyon  of  the  Sacramento  was  cut 
ilown  to  Tiearly  its  present  level,  and  the  mouutains  sculjjtured 
into  existing  forms,  long  before  the  eruption  of  Mount  Shasta 
had  ceased ;  and  a  fieiy  flood  of  lava,  escaping  from  the  southern 
slope  of  ]Mount  Shasta,  entered  the  Sacramento  Canyon,  and 
followed  it  for  50  nules. 

Towering  more  than  a  mile  above  its  neighbors,  perhaps  the 
youngest  of  the  gi'oxip,  Mount  Shasta  is  the  last  of  a  long  series 
of  volcanoes  in  the  Cascade  Range,  stretching  northward  to 
Mouut  Rainier  in  ^Vashiugton.  This  range,  composed  chiefly  of 
volcanic  material,  is  cut  across  by  the  canyons  of  Coh;nd)ia  and 
Klamath  rivers.  In  the  former,  beneatli  a  thickness  of  8,500 
feet  of  lava,  are  found  strata  containing  Tertiary  fossils.  At  the 
southern  base  of  Mount  Shasta,  in  the  canyon  of  McCloud  River, 
similar  beds  of  volcanic  debris  are  found,  but  without  fossils. 
It  is  evident  that  the  main  mass  of  the  Cascade  Range  and  its 
volcanoes  originated  in  recent  geologic  times ;  and  from  the  fact 
that  solfataras,  fiimaroles,  and  hot  springs  are  common  on  their 
slopes,  they  cannot  be  counted  among  wholly  extinct  volcanoes. 

Active  volcanoes  occur  in  Alaska,  but  there  is  some  doubt 
as  to  when  and  where  the  last  volcanic  eruption  iu  the  United 
States  south  of  Alaska  may  have  oecixrred.  The  evidence  seems 
con<'lusive  that  an  eruption  took  place  as  late  as  1843  from 
Monnt  Baker,  and  also  from  Mount  St.  Helens  in  Washington. 

Mount  Shasta  is  a  tyi)ical  example  of  a  large  volcano.  Its 
upbuilding  resulted  from  long-continued  series  of  intermittent 
eruptions.  The  attack  of  the  weather  increased  with  the  height 
of  the  mountain,  and  reached  its  climax  with  the  decadence  of 
volcanic  energy.  During  the  brief  period  in  which  the  weather 
has  exercised  stipreme  control,  the  slopes  of  ]\Iount  Shasta  have 
been  deei)ly  cut  with  canyons,  and  circjues  have  been  outlined 
about  its  lofty  sumniit.  In  the  course  of  geologic  time  it  will 
be  swept  away,  but  for  ages  yet  to  come  it  will  remain  one  of  the 
grandest  mountains  on  the  face  of  the  earth. 


THE    PHYSICAL    GEOGRAPHY    OF    SOUTHERN 
NEW  ENGLAND. 


By  Williaji  Mokkis  Davis. 

Professor  of  Physical  Geography,  Harvard  University. 


Southern  New  England  is  for  tlic  most  ijart  a  slanting  up- 
land, reaching  elevations  of  from  fifteen  hundred  to  two  thou- 
sand feet  in  Vermont  and  westei-ii  New  Hampshire  near  the 
Massachusetts  line,  and  descending  gradually  to  the  coast  on 
the  east  and  south.  The  upland  is  overlooked  by  occasional 
iuountains  of  moderate  height,  such  as  Monadnock:  it  is  inter- 
sected l)y  ninnerous  valleys,  deep  and  narrow  like  that  of  the 
Deerfield,  or  Iji-oad  and  ojien  like  that  of  the  middlti  Conneeti- 
cut.  Its  shore  line  is  ragged,  with  I'centrant  bays  between  pro- 
jecting headlands,  and  sounds  behind  outlj'ing  i.slauds. 

The  heads  of  the  larger  buys  wei'c  early  choscm  as  places  of 
settlement,  and  there  a  number  of  thriving  connnercial  cities 
have  now  grown.  The  low  coastal  border  of  the  upland  near 
the  cities  is  occupied  by  a  comparatively  dense  suburban  and 
rural  population.  The  inner  valleys  serve  as  tlie  paths  of  rail- 
roads leading  to  numerous  manufacturing  villages  and  cities. 
The  higher  parts  of  the  ui)hiiid  are  spai'sely  settled  by  a  decreas- 
ing agricultural  population,  and  the  mountains  above  the  upland 
are  practically  uninhabited. 

THE  UPLAND  OF  SOUTHEKN  NEW  ENGLAND. 

General  Features. — The  gently  slanting  upland  is  the  most 
important  geographical  feature  of  this  region.  Omitting  from 
consideration  for  th<'  jiresent  the  mountains  that  hero  and  there 
overlook  it,  and  the  numerous  valleys  that  are  woi-n  beneath  it, 
let  us  consider  the  form  and  origin  of  the  upland  itself.    Ascend 

(Copyriglit,  1895,  by  American  Book  Company.) 
269 


270 


THK  UPLAND  OF  SOUTHERN  NEW  ENGLAND.        "JTl 

a  hill  that  i-cac-hes  tlic  general  upland  level,  and  noto  how  even 
the  sky  line  is  on  all  sides;  how  moderate  the  ine(iuality  of  the 
surface  would  be  if  it  wei-c  not  for  the  few  mountains  that  rise 
above  it,  and  the  many  valleys  that  siidc  below  it.  Looking 
aroTuid  the  horizon,  the  slightly  rolling  high-level  surfaee  of  one 
hill  after  anothei-  approaches  the  plane  of  the  cireuiai-  sky  line. 
It  re(iuires  but  little  imagination  to  recognize  in  the  successive 
hilltops  the  dissected  remnants  of  a  once  even  and  continuous 
suVface,  beneath  wiiich  the  valleys  of  to-day  have  been  eroded. 
The  former  continuity  of  the  now  separated  hilltops  is  so  mani- 
fest, when  it  is  onee  perceived,  that  it  is  well  to  desci-il)e  tlie  re- 
gion as  an  upland  or  as  a  dinsccted  upland,  thus  emphasizing  the 
original  continuity  of  the  now  dissected  upland  areas,  and  at 
the  sanu^  time  comiteracting  and  corre<'ting  the  belief,  jjiwaleut 
in  the  minds  of  those  Avho  dwell  in  our  valleys,  that  southern 
New  England  is  simply  a  i-eg^on  of  disord(U'ly  hills. 

Not  less  notable  than  the  foi-mer  continuity  of  the  dissected 
upland  is  the  want  of  sympathy  between  its  suiface  and  the 
structure  of  the  rock  masses  of  which  the  ivgion  is  composed. 
The  slopes  and  crests  of  the  hills  often  expose  their  stru(ttural 
rock  ribs  in  jn-ojecting  ledges;  the  disoi-dered  attitude  of  the 
rocks  is  plainly  exhibited  in  stream  banks,  (piai'ries,  and  raili'oad 
cuts ;  but,  however  they  stand,  they  are  evenly  cut  off  when  they 
reach  the  upland  suiface,  just  as  the  fibers  of  a  great  tree  ai"e  cut 
across  at  the  even  surfai-e  of  its  sawed  stimip.  This  is  an  impor- 
tant matter,  for  upon  it  chiefly  timis  the  correct  interpretation  of 
the  oiigin  of  the  upland. 

The  upland  is  most  easilj^  recognized  where  it  stands  at  a 
considerable  elevation,  for  hero  we  find  the  strongest  contrast 
between  hilltop  and  valley  floor.  The  broad,  high-level  areas 
between  the  DecM'tield  and  Westfield  valleys,  or  the  Westfield 
and  Farmington  valleys,  in  western  Massaclnisetts,  offer  admira- 
ble illustrations  of  its  character.  The  upland  can  thence  be 
traced  southward,  ])ast  many  deep,  ti'ench-likc^  vallej's,  such  as 
that  of  the  Naugatuck  above  Watei'bury,  Conn.  It  gi-adually 
descends  to  the  sea  level  at  the  shore  of  Long  Island  Sound. 
The  view  westward  from  the  summit  of  the  Hanging  Hills,  near 
Meriden,  Conn.,  sliows  the  upland  beyond  the  Connecticut  Valley 
lowland  with  a  remarkal)ly  even  sky  line.  It  truly  resend)les  a 
plateau  thereabouts,  and  so  it  may  be  called.  An  excellent  sight 
of  the  upland  farthei-  east  may  be  obtained  from  Gj'eat  Hill,  a 


it 


1 


'/ 


'5^ 


272 


THE    UPLAND   OF    SOl'THEKN    NEW    ENGLAND.  273 

little  novtli  of  Cobalt  station,  ou  the  Air  Line  Railroad,  a  few 
miles  east  of  ^Middletown,  Conn.  Here  attention  is  first  attracted 
by  the  beantiful  valley  of  the  Connecticut  River,  ou  its  way 
to  the  Sound  at  Saybi-ook  (of  wliicli,  more  Ijclow);  but,  on  turn- 
ing to  examine  the  upland  in  which  the  valley  is  sunk,  the  even 
sky  line  is  still  ])erceived  to  be  its  most  striking  characteristic. 
Farther  north,  in  Massachusetts  again,  the  quiet  hill  town  of 
SliutesT)ury,  easily  reached  by  stage  or  on  foot  from  the  Fitch- 
burg  Railroad,  near  by  in  the  valley  of  ]\Iill<M's  River,  commands 
a  wide  prospect  over  the  even  uphnid,  and  down  into  the  valley 
by  whicli  the  upland  is  there  so  deeply  dissected.  Near  Gardner, 
ihi.)  Fitchburg  lini'  passes  over  tlu.'  divide  between  the  basins  of 
Nashua  and  Millers  rivers,  and  traverses  the  upland  for  a  short 
distance.  Broad  views  then  open  out  on  either  side,  presenting 
the  upland  country  in  a  very  different  aspect  from  that  in  which 
travelers  by  rail  oi'dinarily  see  it;  for  most  of  our  railroads  fol- 
low valley  floors.  North  of  Boston,  the  hills  back  of  Waltham, 
Arlington  Heights,  and  the  Middlesex  Fells  as  seen  from  the  hills 
of  Somervillc,  —  or  even  from  the  State  House  dome, —  exliibit  a 
comparatively  even  sky  line,  gradually  descending  eastward  to- 
ward Lynn.  West  of  Narragansett  Bay  the  ujilaiid  has  a  well- 
defined,  even-summit  surface,  gently  descending  southward,  as  in 
Connecticut ;  and  so  on,  at  many  other  places.  Thei'e  is  hardly 
a  village  in  southern  New  England — except  on  the  sandy  low- 
land of  the  southeast — from  which  a  willing  observer  cannot 
see  a  pai-t  of  the  upland  in  an  aftei'iioon's  walk. 

Okigin.  —  Still  postponing  the  consideration  of  the  sunnount- 
ing  mountains  and  the  intrenched  valleys,  let  us  inquire  into  the 
origin  of  the  once  even  surface  of  the  upland.  At  the  time 
before  the  valleys  wei-e  worn  in  it,  it  was  a  broad,  gently  rolling 
plain  of  moderate^  relief,  only  here  and  there  interrupted  by  the 
mountains  that  rose  above  it.  It  cannot  have  then  been  a  young 
marine  plain  formed  under  the  sea  and  revealed  by  uplift,  like 
the  coastal  iilain  which  now  borders  our  southern  Atlantic  and 
Gulf  States ;  or  a  young  lacustrine  plain,  once  the  floor  of  a  lake 
from  which  the  water  has  been  withdrawn,  like  the  desert  plains 
of  Utah  and  Nevada :  for  plains  of  these  classes  consist  of  bedded 
and  loose-textured  sands  and  clays,  whose  nearly  horizontal  strata 
closely  accoi-d  with  their  almost  level  surface.  The  New  England 
upland  consists  of  rock  masses  of  many  different  kinds,  whose 
texture  is  for  the  most  part  thoroughly  indurated,  and  whose  at- 


:.'74  PHYSICAL   GEOGRAPHY   OF   SOUTHERN    NEW   ENGLAND. 

titude  is  gi-eatly  and  irregularly  inclined.  Manifestly  the  ancient 
upland  cannot  be  classed  with  either  marine  or  laciistriue  plains. 

There  are  slanting  or  nearly  level  plains  in  certain  parts  of  the 
world  which  have  been  formed  by  the  weathering  and  wasting- 
away  of  a  mass  of  overlying  rock  layers,  thus  exposing  a  horizon- 
tal or  slightly  inclined  resistant  stratum  of  indurated  rock,  on 
which  further  progress  of  weathering  is  long  delayeil.  Such,  for 
example,  is  the  upland  plain  in  which  the  gorge  of  Niagara  is  cut ; 
but  in  these  stripped  plains,  or  structural  phi'ois,  as  they  may  be 
called,  there  is  necessarily  a  close  sympathy  between  the  shape 
of  the  surface  and  the  attitude  of  the  resistant  stratum  which 
determines  it.  Surely  this  is  not  the  case  in  New  England ;  for 
here,  although  the  rocks  are  indurated,  they  stand  in  all  attitudes 
with  respect  to  the  upland  surface, — here  inclined  to  the  east, 
there  to  the  west ;  here  gently  slanting,  there  steeply  jilunging  or 
even  vertical.  The  generally  even  surface  of  the  upland  shows 
practically  no  sympathy  with  this  diversity  of  structure,  but 
passes  indifferently  across  all  the  inclined  rock  masses.  The  New 
England  upland  cannot,  therefore,  have  been  a  structural  plain. 

There  is  a  kind  of  plain  that  results  from  the  destructive  ac- 
tion of  weather  and  water,  by  which  any  laud  area,  whatever  its 
original  form,  is  worn  down  so  smooth,  and  so  close  to  sea  level, 
that  it  cannot  be  worn  any  lower.  Although  thus  easily  and 
simply  stated,  the  possiliility  of  producing  plains  in  this  manner 
is  one  from  which  an  unaccustomed  mind  instinctively  shrinks  on 
account  of  the  enormous  time  that  it  must  recpiire.  The  small 
attention  at  present  given  to  land  sculjiture  in  the  study  of 
geography  is  here  to  blame.  Early  grammar-school  teaching 
should  present  the  general  idea  of  weathering  of  rocky  hillsides 
and  the  transportation  of  the  rock  waste  down  the  slopes  to  the 
sea,  thus  preparing  the  way  for  understanding  the  great  results 
of  these  simple  processes  when  long  continued ;  yet  nowadays 
even  the  teacher  may  hesitate  to  think  that  land  erosion  has 
anywhere  in  the  world  advanced  so  far  as  to  consume  high  hills, 
and  reduce  them  to  lowland  plains.  This  idea  is  not  conunonly 
familiar,  and  it  is  generally  given  a  cool  reception  when  first 
met.  Many  text-ljooks  now  in  use  cite  deep  valleys  as  the  best 
examples  of  long-continued  erosion;  but  it  is  manifest  that, 
whei'e  the  valley  sides  have  wasted  away  so  as  to  consume  the 
interstream  hills,  a  greatly  increased  period  of  erosion  nmst  have 
elapsed.    Worn-down  countries  or  plains  of  denudation,  and  not 


THE  UPLAND  OF  SOUTHERN  NEW  ENGLAND,         275 

deep  valleys,  should  therefore  l)e  iutroduced  as  examples  of  what 
erosion  oau  do  if  time  enough  is  allowed ;  and  the  earlier  this  im- 
portant generalization  becomes  familiar  to  young  scholars,  the 
more  freqnentl}'  and  easily  can  they  apply  it  afterwards. 

Now  we  must  inquii'e  whether  the  ancient  upland  of  New  Eng- 
land, before  the  valleys  were  cut  in  its  then  even  surface,  was  a 
plain  of  denudation  ;  and  the  methods  of  this  or  of  any  similar 
inquiry  should  be  cai'efully  and  consciously  perceived.  We  must, 
on  the  one  hand,  study  the  j^hysical  features  of  the  region  under 
consideration  until  they  can  lu^  justly  generalized ;  we  nuist,  on 
the  other  hand,  reason  out  wliat  would  be  the  essential  pecul- 
iarities of  a  plain  of  completed  denudation,  guiding  ourselves  in 
this  inquiry  by  accepted  geologittal  principles.  We  must  then 
compare  the  results  of  these  two  lines  of  work;  and  if  the  ex- 
pectations of  oui-  reasoning  match  t  he  generalized  facts  of  obser- 
vation, it  may  lie  as  a  rule  fairly  maintained  that  the  reasoning 
has  led  to  a  correct  exphi nation  of  the  facts,  or  at  least  that  the 
explanation  may  lie  adojtted  provisionally  while  it  undergoes 
further  scrutiny.  This  method  has  already  guided  us  in  inquir- 
ing whether  the  New  England  upland  was  originally  a  marine 
coastal  plain,  a  lacustrine  plain,  or  a  sti-ipped  sti'uctural  plain,  the 
result  being  negative  in  each  case. 

The  facts  of  form  and  structure  of  the  New  England  uiilaiid 
have  already  been  sufficiently  stated  in  generalized  form.  They 
may  be  veritied  l)y  hundreds  of  observers  in  all  jKirts  of  Massa- 
chusetts (except,  as  already  stated,  in  the  sandy  southeastern 
lowland),  Rhode  Island,  and  Connecticut,  as  well  as  in  southern 
Vermont  and  Now  Hnnqishire.  The  theoretical  expectations 
regarding  a  plain  of  denudation  must  now  be  reasoned  out. 
Whatever  the  initial  form  and  structure '  of  the  region,  it-  must 
be  worn  lower  and  low(n-  as  long  as  it  stands  still  with  resjiect 
to  sea  level,  and  suffei-s  under  the  genei-al  attack  of  weather  and 
water.  The  valleys  are  deepened  first,  until  the  slope  of  their 
rivers  is  reduced  to  a  gentle  grade.  ^Phe  hills  are  much  more 
slowly  worn  down;  but  as  long  as  they  have  a  slope  to  the 
streams,  and  as  long  as  the  streams  descend  to  the  sea,  the  wast- 
ing of  the  hills  continues.    The  most  resistant  rocks  are  the  last 

1  It  should  hi'  (ilistMvc.l  thiit  the  tenu  .•.Inwdirc  is  usimI  throughout  this  moiio- 
Sraph  to  refer  to  the  internal  arranKoraent  of  roek  masses,  and  not  to  the  succession 
of  superficial  features,  as  it  is  sometimes  employed  in  geogi-aphical  descriptions.  The 
latter  use  is  objectionable. 


271)    PHYSICAL  GEOGRAPHY  OF  SOUTHEKN  NEW  ENGLAND. 

to  be  worn  down,  but  all  must  go  in  time.  When  at  last  worn 
close  to  sea  level,  the  surface  must  be  practically  indifferent  to 
the  attitude  of  the  rock  masses.  There  can  be  no  essential  sjtu- 
pathy  between  surface  and  structure,  siich  as  has  been  stated 
to  characterize  young,  unworn  marine  or  lacustrine  plains,  or 
stripped  plains.  The  almost  sea-level  surface  to  which  a  region 
may  ultimately  be  reduced  must  pass  indifferently  across  the 
structure  of  its  rock  masses. 

The  Upland  is  an  Old  Peneplain. — This  peculiar  feature 
— indifference  of  even  surface  form  to  disorderly  internal  struc- 
ture— now  appears  to  be  a  common  characteristic  of  the  old 
upland  of  southern  New  England,  and  of  a  theoretical  plain  of 
denudation :  hence  the  upland  may  be  fairly  enough  provisionally 
regarded  as  an  ancient  plain  of  denudation.  It  should  be  noted, 
however,  that,  accortling  to  this  exi)lanation,  it  is  not  necessary 
to  suppose  that  the  upland  of  New  England  or  of  any  other 
similar  region  was  worn  down  absolutely  and  completely  to  sea 
level,  or  haselcrcl,  as  it  is  generally  called.  The  process  of 
denudation  may  be  interrupted  in  a  penultimate  stage,  when  the 
region  had  been  rediiced  to  moderate  i-elief,  and  before  it  had 
been  worn  down  perfectly  flat.  It  might  then  be  called,  not  a 
plain,  but  a  pexcplain,  of  denudation. 

The  discordance  of  the  upland  surface  and  the  rock  structure 
is  so  marked  a  characteristic  of  New  England,  and  is  so  fuUy  and 
reasonably  explained  bj'  the  theory  of  the  penei^lain,  that  it 
would  be  fail"  to  conclude  at  once  that  the  formerly  even  upland 
really  was  a  peneplain,  worn  down  under  the  long  attack  of  the 
weather,  if  it  were  not  for  a  possibility  that  smooth  plains  of 
denudation  may  be  produced  b}^  another  process,  namel_v,  by  the 
attack  of  the  seashore  waves.  If  a  continental  mass  stand  stiU 
for  a  long  time  with  respect  to  sea  level,  while  the  sim  continues 
to  shine,  the  winds  to  blow,  and  the  waves  to  roll,  then  the  mar- 
gin of  the  continent  will  suffer  from  the  beating  of  the  surf :  the 
sea  will  encroach  on  the  land,  eating  it  away,  and  reducing  it  to 
a  comparatively  smooth  submarine  platform  at  a  moderate  depth 
beneath  the  water  surface.  May  not  the  New  England  upland 
have  been  formed  in  this  way,  and  afterwards  raised  from  be- 
neath the  sea!  The  surface  of  the  submarine  iilatform  would, 
like  that  of  the  subaerial  peneplain,  be  indift'erent  to  the  rock 
structures  across  which  the  shore  waves  had  cut  their  way :  hence 
the  chief  test  on  which  we  relied  for  detection  of  the  peneplain 


THE  UPLAND  OF  SOUTHEKN  NEW  ENGLAND.        277 

does  not  serve  to  distinguish  it  from  the  jilatfonn.  What  we 
now  need  is  some  further  test  by  means  of  wliich  these  two 
kinds  of  plaius  of  denudation  may  be  discriminated. 

Tlie  needed  test  is  found  in  the  ari-angeincnt  of  the  rivers; 
but,  while  the  argument  thus  far  pursued  is  essentially  simi>le,  its 
fui'lher  extension  is  unfortunately  comijlicated,  and  partieularly 
so  in  its  application  to  New  England.  It  nuist  suffice,  therefore, 
to  present  it  only  in  outline. 

During  the  long-continued  attack  of  the  weather  necessary 
for  the  pi-odi;ction  of  a  subaerial  peneplain,  the  little  streams 
gnaw  at  their  head  waters,  and  search  out  the  weaker  rock 
masses  on  which  to  extend  their  valleys.  As  these  growing 
valleys  increase  in  length,  they  thus  become  well  adjusted  to  the 
structure  of  the  region  that  they  drain.  Penei»lains  have,  there- 
fore, not  only  a  surface  form  that  is  indiifer(>ut  to  internal  struc- 
ture :  they  have  also  a  drainage  system  that  is  for  the  most  part 
well  adjusted  to  the  weaker  parts  of  the  structure;  and  this 
adjustment  is  nuiintained  or  even  furtlu>r  improved  if  a  new 
uplift  of  the  region  afterwards  allows  dee])er  dissection. 

During  the  long-continued  attack  of  the  shore  waves  necessary 
for  the  production  of  a  l)road  sul)marine  platform,  the  valleys  are 
extinguished  as  tlu^  land  is  cut  away.  When  the  platform  is 
afterwards  raised  above  sea  level,  and  streams  gather  on  it  again, 
they  assume  such  coursers  as  the  slight  inequalities  of  the  njdifteil 
platform  shall  determine,  and  htmce  have  about  as  indefinite  re- 
lation to  structure  as  the  surface  has.  Uplifted  platfoi-ms  have 
thei-efore,  when  they  arise  above  the  sea,  and  for  some  time 
thereafter,  a  drainage  system  that  is  essentially  iiidiftVi-ent  to  the 
rock  structure. 

It  would  be  easy  to  apply  the  test  thus  deduced  if  the  geologi- 
cal structuiv  of  New  England  were  as  simple  as  that  of  middle 
Pennsylvania;  but  unfortunately  such  is  not  the  case.  The 
arrangement  of  the  rock  masses  in  the  New  England  upland  is 
excessively  com})licat(Hl ;  moreover,  the  glacial  invasion  (of  which, 
more  below)  has  been  a  disturbing  agency  by  throwing  many 
streams  into  new  courses.  It  would  be  venturesome  at  jire'sent 
to  make  any  gelieral  statement  regarding  the  adjustment  or  in- 
difference of  our  streams  and  structures,  and  the  question  would 
have  to  remain  in  doubt  were  it  not  for  evidence  tliat  may  be 
borrowed  from  New  Jersey  and  Pennsylvania.  The  ujiland  of 
New  England  is  continuous  with  corresponding  uplands  in  those 


278    PHYSICAL  GEOGRAPHY  OF  SOUTHERN  NEW  ENGLAND. 

States,^  where  the  river  test  has  been  suoeessfiilly  applied.  The 
subaerial  origin  proved  for  the  more  southern  peuepkiin  may  be 
fairly  aeoei)ted  for  the  more  northern  one  as  well.'- 

KeFLECTIONS    SUGGESTED    BY   THE    OrIGIN    OF    THE    UPLAND. — 

^VTieu  the  belief  clearly  enters  the  mind  that  the  upland  of 
southern  New  England  is  really  a  peuej^lain  of  denudation,  it 
arouses  a  munber  of  interrogative  reflections.  In  the  flrst  place, 
inquiry  springs  up  as  to  the  amount  of  mateiial  that  has  been 
worn  away  in  the  production  oi'  the  ]>eneplain.  Look  once  more 
at  the  character  of  the  upland  rocks :  they  are  crystalline  schists 
and  gneisses  for  the  most  part,  whose  minerals  are  never  formed 
at  the  surface  of  the  land  or  on  the  floor  of  the  sea,  but  only  deep 
within  the  crust  of  the  earth  under  great  pressui'e  and  at  com- 
paratively high  temperatures.  Besides  these  rocks,  there  are 
many  intrasive  gi-auites,  felsites,  diorites,  and  other  igneous 
rocks;  not  loose-textured,  slaggy,  and  ashy,  like  the  eruptive 
rocks  of  volcanoes,  Init  compact  and  dense-textmvd,  as  if  they 
had  cooled  under  the  heavy  pressure  of  a  gi'eat  superincumbent 
load.  It  is  only  by  long-<'ontinued  and  extensive  denudation 
that  the  surface  of  the  land  can  ai)j)roach  rocks  of  deep-seated 
origin :  hence  it  may  be  concluded  that  the  initial  siu'faee  of  the 
region  stood  high  above  the  surface  of  the  peneplain.  Whenever 
the  even  sky  line  of  the  iipland  is  spread  before  the  observer,  it 
should  be  borne  in  mind  that  the  i-ocks  now  exposed  to  the  light 
of  day  were  for  long  ages  biuied  in  inner  darkness. 

Was  the  region,  before  the  great  denudation  was  accom- 
pUshed,  a  rocky,  even-topped  plateau,  or  a  rugged  uiouutain 
range!  Look  again  at  the  attitude  of  New  England  rocks,  re- 
membering that  typical  plateaus  like  those  of  Utah,  New  Jlexico, 
and  Arizona,  have  horizontal  structure,  while  tj-jncal  mountain 

•  The  Kittatinny  ])i'iifi>laiu.  See  Tl>e  Northern  Appalachiaus,  by  Bailey  Willis 
(National  Geographie  Monojcraphs,  No.  6,  p.  1S7). 

-  The  full  liiscnssion  of  this  problem  in  its  application  to  New  England  has  not 
yet  been  undertaken.  Along  the  southern  border  of  the  upland,  a  number  of  rivers 
that  enter  Long  Island  Sound  seem  to  exhibit  a  rather  marked  indifference  to  struc- 
ture,  from  which  the  origin  of  the  upland,  or  at  least  of  that  part  of  the  upland,  as  a 
submarine  platfomi,  might  be  argued.  But  it  may  be  answered  that  this  indifference 
of  streams  to  structure  can  be  explained  by  superposition  through  the  former  in- 
land extension  of  the  Cretaceous  strata  now  seen  in  Long  Island ;  and  that  the  Cre- 
taceous sea  may  have  gained  access  to  the  region  passively  by  the  submergence  of  a 
previously  denuded  peneplain,  as  well  as  actively  by  cutting  its  way  inland  during 
the  production  of  a  platform.  No  certain  settlement  of  this  involved  question  can 
be  given  at  present. 


THE  UPLAND  OF  SOUTHERN  NEW  ENGLAND.        279 

liiiiges  like  the  Alps  and  Himalayas  are  regions  of  deformed 
structure.  Ancient  New  EngUmd  certainly  belonged  to  the 
hitter  class.  The  disoi-derly  and  stc('])ly  inclined  rock  masses 
may  be  seen  at  a  hundred  points  on  liiUlops  and  valley  sides,  in 
stieam  Ijeds,  railroad  cuts,  and  quai-ries.  The  valleys  of  the 
Housatonic,  Farmington,  "Westfield,  and  Deerlield  rivers  all  ex- 
pose deep  sections  in  the  Avestern  upland.  E.xtensive  (piarries, 
such  as  those  of  Monson  in  the  upland  east  of  Si)ringfiel(l,  are 
well  worth  visiting  t'oi'  the  plain  views  that  they  afford  of  rock 
structure  and  attitude.  The  headlands  of  the  coast  frequently 
expose  clean-swei)t  ledges,  where  the  deformed  rocks  can  be  ad- 
miraldy  studied.  They  all  teach  the  lesson  of  severe  disturbance, 
as  differeid  as  jtossilile  from  the  jHacidity  tluit  jirevails  among 
the  .mcient  sedimentary  strata  of  the  Ohio  N'alley,  where  layer 
lies  on  layer  in  almost  undisturbed  horizontal  position. 

The  NeAV  England  rocks  are  not  only  deformed  in  mass:  they 
exhibit  also  at  many  i)laces  the  minute  internal  <leformities  so 
characteristic  of  ivgions  that  have  l)een  crushed  under  a  great 
overlying  load,  and  so  prevalent  in  regions  that  are  mountainous 
to-day.  On  Hoosac  Mountain  t]ier(>  is  an  old  pudding  stone  or 
conglomerate  whose  once  round  pel)bles  ;ne  now  di'awn  out  into 
strips,  the  rock  assuming  the  charncter  of  a  gneiss.  Among  tlie 
Berkshire^  Hills  ancient  slates  are  gnarled  and  crinkled  into 
schists.  At  many  points  cleavage  is  more  or  less  perfectly 
developed  in  the  finer-grained  rocks. 

The  crushing  forces  that  caused  the  greater  and  smaller 
deformities  cannot  have  been  exerted  after  the  peneplain  was 
produced,  for  in  that  event  they  would  have  deformed  the  upland 
surface.  The  deformation  of  New  England  nnist  have  taken 
place  liefore  the  great  denudation.  During  the  period  of  most 
energetic(leformation,Nc\vEngl;ind  must  li;ive  had  as  tlioi'oughly 
a  mountainous  form  as  it  still  has  a  mountainous  structure.  In- 
deed, the  most  ])robable  conclusion  thatciui  be  reached  regarding 
the  anci<!nt  topogi'aphy  of  the  region  raises  its  peaks  to  truly 
Alpine  heights,  clothes  their  upper  slopes  with  snow  fields,  and 
fills  their  valleys  with  glaciers;  and  all  these  features  should  l)e 
restored  in  the  pictures  that  tlu^  attentive  observer  menttdly 
sketches  in  his  effort  to  represent  the  ancestry  of  the  upland. 
Very  slowly  were  the  ancient  mountains  raised;  much  more 
slowly  were  they  worn  down,  until  now  onlj'  their  base  remain.s. 
New  England  is  a  worn-out  niountnin  range. 


280  PHYSICAL,   GEOGRAPHY    OF   SOUTHEKN    NEW    ENGL.VND. 

The  Peneplain  in  Geogkaphical  Study.  —  It  is  worth  while 
to  stop  our  interrogative  reflections  here  for  a  few  moments  to 
note  the  effect  of  this  intorprotation  of  the  New  Eiighuid  uphmd 
on  the  usual  consideration  of  mountains  in  our  geographical  text- 
books. It  is  ciistomary  to  treat  mountains  empiricall}-  as  fixed 
geographical  forms,  permanently  set  upon  the  earth's  surface. 
Such  terms  as  nhl  nioioitaiiis,  or  ironi-oi(t  nioioitains,  are  seldom 
employed :  the  regions  where  these  terms  would  be  appropiiate 
are  vaguely  desci-ibed  as  hilly  districts,  with  no  sufficient  indica- 
tion of  their  associated  features.  As  a  result,  the  scholar  gathers 
no  understanding  of  the  nature  of  a  region  like  Xew  England ;  for 
the  characteristics  by  which  its  hills  are  distinguished  from  hills 
of  other  kinds,  like  those  of  the  dissected  portions  of  our  South- 
ei'u  coastal  plain,  are  not  clearly  set  before  him.  The  empirical 
treatment  of  geography  ordinarily  adopted  may  be  compared 
to  an  irrational  system  of  botany  that  would  place  spi'outing 
acorns,  full-grown  oaks,  and  decayed  oak  stumps  under  different 
species.  This  is  so  manifestly  alisurd  that  it  seems  to  have  no 
relation  to  the  existing  methods  in  geography,  and  yet  it  is  a 
very  fair  illustration  of  them.  The  young  ridges  of  southern 
Oregon,  hardly  altered  by  denudation  from  the  constructional 
forms  given  Ijy  ilislocatiou  and  upheaval ;  the  Aigorous  Alps,  long 
and  severely  deformed,  and  now  deeply  trenched  by  adolescent 
vallevs;  the  old  mountains  of  Xew  England,  lomj  and  severelv 
deformed,  and  now  broadly  denuded  till  only  their  liases  remain, 
— these  three  examples  of  mountain  fonii  may  be  fairly  likened 
to  the  sprouting  acorn,  the  mature  oak,  and  the  decayed  oak 
stump ;  and  yet  it  is  not  the  fashion  to  emphasize  these  rational 
relationships  in  the  ordinary  method  of  teaching  geogi-aphy. 
Geography  still  retains  too  much  of  its  old-fashioned,  irrational 
methods :  it  has  not  kept  pace  witli  the  advance  made  by  geology. 
In  spite  of  what  the  geologist  has  learned  abi)ut  the  evolution 
of  geogra^ihical  forms,  the  geographer  still  too  generally  treats 
them  empirii-ally,  and  thus  loses  acquaintance  with  one  of  the 
most  interesting  i)hases  of  his  su])ject. 

The  New  England  ujiland,  recognized  as  a  worn-down  moun- 
tain region, — a  peneplain, — soon  comes  to  have  value  as  a  typi- 
cal example  of  this  kind  of  geographical  form ;  and  every  such 
addition  to  the  geograi)her's  stock  of  t^'jies  increases  his  appre- 
ciation of  geography.  In  the  beginning  of  elementary  geography 
only  a  few  simple  t j^jes  are  described ;  but,  as  the  woi-k  advances, 


THE  UPLAND  OF  SOUTHERN  NEW  ENGLAND.        281 

more  complicated  types  should  be  introduced,  otherwise  the  sub- 
ject will  always  remain  in  a  childish  stage.  Rivers  are  early 
taught  by  the  desciiption  of  some  average,  mature  example ;  but 
in  later  years  rivers  of  many  kinds  and  in  yiany  stages  of 
development  should  become  familiar.  ( 'oast  hues  are  at  first 
taught  sinii)ly  (IS  the  margin  of  tliclaud;  Itnt  afterwards  tlicy  may 
tie  elaljorately  suljdividcd  and  classiiiod  according  to  their  origin 
and  evolution.  80  with  mountains:  a  good  vigorous  mountain 
range,  shown  in  pictui-es  and  desci-iljcd  in  nairative  form  rather 
than  in  terse  definition,  properly  intro(hi<'es  this  lai-ge  geograjilii- 
cal  family  to  young  scholars;  but  later  on,  many  kinds  of  moun- 
tains must  be  recognized,  young  and  old,  as  well  as  mature ;  and 
of  old  moimtains  no  better  example  can  be  found  tlian  familiar 
New  England.  More  will  be  said,  later  on,  of  this  important 
matter  of  equipping  the  student  of  geography  with  a  good 
assortment  of  type  forms;  but  w(»  must  now  return  to  matter 
more  immediately  in  hand. 

The  Monadnocks. — In  si)ite  of  all  that  has  been  written,  it  is 
still  natural  that  the  idea  of  wearing  down  a  great  Tuountain 
I'ange  should  Ije  accepted  ratliei'  slowly.  It  is  difiicidt  to  believe 
that  all  the  hardest  mountain  nuclei  can  waste  away.  Some  nn- 
consumed  remnants  of  the  ancient  mountains  of  New  England 
are  naturally  looked  for,  and  they  ai-e  no  sooner  looked  for  tliau 
found.  There  is  hardly  any  comprehensive  view  of  the  upland 
that  does  not  reveal  a  few  hills  surmounting  the  sky  line  by  some 
small  measure  of  height ;  and  in  certain  i)laces  the  remnants  still 
preserve  a  commanding  elevation.  One  of  the  best  points  of  view 
in  New  England  for  the  exhibition  of  the  even  upland  and  the 
occasional  remnant  mountains  tliat  rise  above  it  is  Massamet,  or 
Bald  Mountain,  near  Shell)urne  Falls,  in  northwestern  Massachu- 
setts.' To  the  eastward,  beyond  the  ('oniHu-ticut  Valley,  the  sky 
line  of  the  upland  forms  a  lioi'izon  almost  as  even  as  tliat  of  the 
ocean;  Imt  beyond  in  tlie  hazy  distance  rises  the  blue  dome 
of  Wachuscitt,  an  isolated  ennnence.  Still  more  striking  is  the 
beautifid  cone  of  Monadnock  in  the  northeast,  trnl>'  of  no  great 

,  '  Tho  [icoplo  (if  tliis  inamifiicturiiif;  town  cm  llip  Deerfield  River  havp  laiil  nut  an 
excellent  jiHtli  up  the  hillside,  thi'ou>ch  the  woods,  to  a  hij^h  tower  huiU  on  the  sum- 
mit, from  which  a  broad  prospect,  uninterrupted  by  trees,  is  opened  on  all  sides. 
The  round  trip  from  the  railroad  station  may  be  made  on  foot  comfortably  in  four 
hours.  —  an  hour  and  a  half  for  ascent;  the  same  time  on  the  tower,  ma])  in  liand, 
stiidyiuf;  the  view;  and  an  hour  for  descent.  Much  of  the  patliway  is  sliaded.  The 
morning  hours  are  best  for  the  walk. 


282     PHYSICAL  GEOGKAPHY  OF  SOUTHERN  NEW  ENGLAND. 

height  among  the  mountains  of  the  world,  yet  here  imposing 
from  the  strength  with  which  its  solitajy  pile  emphasizes  the 
evenness  of  the  upland  that  it  surmounts.  It  might  well  be  mis- 
taken for  a  vokt^no,  so  symmetrioal  are  its  slopes  as  seen  from 
Massamet ;  but,  far  from  having  been  heaped  up  on  a  once  level 
upland,  ]\[onadn(K'k  and  its  fellows  are  the  last  remaining  hard- 
rock  kernels  of  once  much  higher  mountain  masses,  now  nearly 
worn  away. 

There  are  not  many  Monadnocks  in  southern  New  England : 
the  rolling  upland  is  seldom  dominated  by  any  strong  summits. 


KiG.  o.  —  Moiiailuock,  from  uiar  Keiuu,  X.  H. 
(Photographed  by  J.  A.  French.) 

The  view  from  Great  HiU,  near  Cobalt,  Conn.,  already  mentioned, 
discloses  no  remnant  mountains  distinctly  interrupting  the  up- 
land sky  line.  Diufee  Hill,  in  north-centr;\l  Rhode  Island,  is  the 
highest  Monadnock  of  that  State.  The  Ladd  Observatoiy,  on  one 
of  the  hills  of  Providence,  commands  an  excellent  view  of  the  up- 
land sky  line  beyond  the  Rhode  Island  boundary  in  southeastern 
Massachusetts.  Only  one  little  hiU  in  the  distance  distinctly 
sm-mounts  the  upland  level,  yet  the  sharp  dej)arture  of  the  hih 
from  the  ride  of  the  A-iew  attracts  to  it  an  amoi;nt  of  attention 
that  is  quite  out  of  proportion  to  its  small  size.  Blue  Hill,  a 
short  distance  south  of  Boston,  is  the  most  striking  Monadnock 
east  of  "Worcester  and  south  of  the Xew Hampshire  line,  the  upland 
in  its  neighborhood  being  well  displayed  in  the  hilltops  above 


THE  VALLEYS    m  THE   UPLAND.  2S3 

Declhaiu.  But  on  i)iissiug-  northward  into  \'erniont,  New  Hanijp- 
sliire,  and  Maine,  Monadnooks  are  eonnnon.  The  Wliite  Moun- 
tains seem  to  be  only  a  chister  of  uuconsumed  remnauts;  the 
scattered  mountains  of  northern  Elaine  are  pi-ohaMy  of  the  same 
kind;  tlie  divi(h^  ])etween  Connecticut  and  Cliaiiiplain  (h-ainage 
in  Vermont  appears  to  lie  ou  the  northern  extension  of  the  westei-u 
Uphmd  of  ^Massachusetts;  and  tlie  peaks  of  tlie  (xreeii  Mountains 
are  presumalily  Monadnocks,  hke  (xreyh>ck  and  Mount  P^verett 
farther  south.  But,  hi  spite  of  the  nearness  of  these  noi-thern 
States,  they  have  not  heen  (>xplored  with  the  upland  peneplain 
and  the  Monadnocks  in  mind.  No  definite  statement  can  at 
present  be  given  as  to  the  altitude  of  the  ujjland  in  northern 
New  England,  or  as  to  the  degree  of  perfection  that  it  attained. 
The  region  invites  careful  investigation. 

The  sunnuits  of  the  Monadnocks  ott'ei'  extended  views  over 
the  upland,  and  they  should  hv  utilized  as  far  as  possible  in 
teaching.  An  excursion  to  the  top  of  Wachusett,  for  ('xami>le, 
is  easily  accomplished  from  a  number  of  cities  and  towns  in  its 
neighborhood,  and  may  be  made  extremely  profitable  to  a  class 
of  young  scholars.  But  just  as  we  should,  for  the  time  being, 
assume  the  mental  and  moral  attitude  of  a  people  if  we  would 
truly  appreciate  their  history,  so  we  shotild  stand  neai-  the  level  of 
the  upland,  and  not  at  that  of  a  Monadnock  above  it  or  of  a 
valley  below  it,  if  we  woidd  truly  ai)preciate  it  as  a  pen<>])laiH. 
Mounds  that  rise  but  little  over  their  sui-roundings,  like  Mas- 
samet  near  Shelburne  Falls,  or  Great  HUl  near  Cobalt,  hardly 
deserving  to  be  called  Monadnocks,  offtM-  iho  best  opportunity 
for  recognition  of  the  real  features  of  the  upland. 

THE   V.U.LEYS   IN   THE   UPLAND. 

The  Slanting  Elevation  of  the  Peneplain. — The  most 
important  I'eflection  suggested  by  the  view  of  the  upland  pene- 
plain of  southern  New  England  is  yet  to  be  stated,  altliough  it 
can  hardly  have  escaped  the  attention  of  the  reader.  The  pene- 
plain has  been  accounted  for  as  a  surface  of  denudation,  worn 
down  about  as  low  as  is  possible  by  the  processes  of  sul)ai''rial 
denudation  ;  reduced  to  a  comparatively  smooth  lowland  of  faint 
relief,  close  to  the  level  of  the  sea.  Yet  it  is  now  a  slanting  up- 
land rising  distinctly  above  sea  level,  and  its  surface  is  no  longei- 
even  and  continuous,  but  is  dissected  by  numerous  valleys.     Tn 


2S4  PHYSICAL   GEOtlKArHV    t)F    SOUTHEKN    NEW    ENdLAND. 

the  latest  stage  of  the  development  of  the  peneplain,  the  rivers 
must  liave  Mowed  on  broad  flood  plains,  adjoiiitnl  by  gently 
rolling  low  country  on  either  side,  liere  and  there  surmounted  by 
some  surviving  Mouadnoek.  The  very  facts  that  the  peneplain 
is  now  slanting  upland,  not  a  lowland,  and  that  it  is  strt)ngly  dis- 
sected by  many  valleys,  at  once  suggest  that  it  has  been  boilily 
elevated  from  its  former  to  its  present  altitude  so  as  to  slant 
gently  to  the  soutli  and  southeast;  and  that  in  consequence  of 
this  elevation  tlie  rivers  that  were  powerless  to  cut  tlieir  channels 
any  tlceper  while  the  region  was  still  a  k)wland  have  been  revived 
into  a  new  cycle  of  activity  now  tliat  tiie  region  has  become  an 
u]>l;nid.  Only  in  this  way  can  the  dissection  of  the  upland  be 
accounted  for.  Uow  the  uplift  was  caused,  or  wlij-  it  came  at 
one  time  rather  than  another,  no  one  knows.  Tliere  is  nothing 
to  suggest  that  volcanic  action  liad  anything  whatever  to  do  with 
it.  There  is  nothing  to  suggest  tliat  it  was  violent  or  rapid,  or 
attended  by  notable  tremors  or  eartlupiakes.  It  can  only  be  said, 
that,  after  a  long  time  of  comparative  quiet,  further  smoothing 
of  the  peneplain  was  prevented  by  the  occurrence  of  an  ui)lift  of 
unknown  origin.  The  general  date  of  the  uplift  can  be  given  in 
geological  chronology ;  but  it  is  siiflficient  here,  if  any  one  asks 
when  the  uplift  occurred,  to  say,  "  It  must  have  been  long  enough 
ago  for  the  valleys  to  have  been  worn  out  since."  Tliat  is  a  good 
geographical  answer. 

It  is  particularly  important  to  recognize  that  the  evidence 
leading  to  the  belief  in  the  uplift  of  the  old  peneplain  is  found 
entirely  in  the  form  of  the  region  itself.  It  is  not  a  conclusion 
based  on  the  (>vidence  of  uplifted  strata  bearing  marine  fossils; 
for,  while  such  fossiliferous  strata  occur  both  of  ancient  and 
modern  dates,  they  do  not  bear  on  this  part  of  our  problem.' 
The  uplift  is  known  to  liave  occurred  simply  because  the  process 

'  For  example,  among  the  doformeil  roeks  of  tlie  ujiland  tliere  are  ancient  fossil- 
iferous strata  at  various  points.  Certainly  tlieir  fossils  show  that  they  liave  been 
uplifted  with  respeet  to  the  sea  in  which  they  were  deposited ;  V)ut,  if  it  were  not  for 
the  evidence  found  in  the  form  of  the  dissected  peneplain,  it  might  be  supposed  that 
their  present  altitude  above  sea  level  had  been  given  once  for  all,  with  the  deforma- 
tion of  the  ancient  mountains,  and  that  these  fossil-bearing  rocks  still  stand  above 
sea  level  only  because  they  have  not  yet  been  ■(vorn  down  from  the  height  originally 
given  to  them.  Indeed,  this  opinion  was  very  generally  though  rather  vaguely  held 
until  fifteen  or  twenty  years  ago.  The  adojition  of  the  oiiiuion  now  prevalent  is 
entirely  due  to  the  recognition  of  the  evidence  based  on  the  form  of  the  peneplain. 
The  first  explicit  application  of  this  evidence  to  the  case  of  New  England  was.  I  be- 
lieve, made  by  Professor  B.  K.  Emerson,  of  Amherst  College. 


THE   VALLEYS   IN   THE   UPLAND.  285 

of  production  of  the  peuepluiu  demands  that  the  region  stood 
lower  than  now  while  the  great  denudation  was  in  progress. 

Those  who  have  not  studied  geography  outdoors  may  find 
some  difficulty  in  accepting  tliis  argument.  They  are  accustomed 
to  saying,  "  Geologists  tell  us  that  so  and  so  has  happened ;  "  but 
it  would  be  a  sad  mistake  to  treat  this  problem  in  so  irresponsible 
a  manner.  When  a  teacher  comes  to  the  problem  of  the  right- 
angled  triangle,  he  does  not  say,  "  Geometers  toll  us  that  the  sum 
of  the  squares  is  so  and  so :  "  he  proceeds  to  explain  the  demon- 
stration. It  is  satisfactory  to  his  own  mind:  he  accepts  it  fully, 
and  is  willing  to  be  held  responsible  for  it.  No  teacher  of 
geography  should  mention  such  a  feature  as  an  uplifted  and  dis- 
sected peneplain  until  she  is  fully  convinced  of  its  actual  occur- 
rence, and  of  the  reality  and  sufficiency  of  the  processes  by  which 
it  is  explained.  No  teacher  in  southern  New  England  should  .say 
anything  about'  the  home  peneplain  to  her  scholars  until  she 
can  say,  not,  "  Geologists  tell  us  so  and  so,"  but,  for  example, 
"  You  can  easily  understand  that  the  old  peneplain  has  been  up- 
lifted, for,  if  it  had  not  been,  no  valleys  could  have  been  worn  in 

it.    A  good  place  to  see  this  is ."    While  the  teacher  doubts, 

the  scholars  find  her  explanations  "  too  hard."  When  the  teacher 
has  an  easy  mind,  the  scholai-s  will,  I  am  convinced,  find  no  diffi- 
culty in  following  the  essence  of  all  the  explanations  here  ottered, 
provided  thej'  are  presented  very  slowly,  with  plcMity  of  local 
illustrations  in  the  field,  and  plenty  of  time  for  their  digestion, 
part  by  part.  The  explanations  and  illustrations  ultimately 
leading  to  such  problems  as  are  here  treated,  should  be  begun  in 
the  earliest  nature  study,  and  reviewed  so  frequently,  and  with 
such  expansion  of  application,  that  the  scholar  makes  his  way 
to  the  understanding  of  the  dissected  peneplain  step  by  step,  as 
naturally  and  easily  as  he  walks  to  school. 

Only  after  this  long  introduction  can  the  study  of  the  valleys 
of  New  England  be  properly  undertaken.  They  have  been  laid 
aside  tVom  consideration  for  a  number  of  pages,  but  now  they 
may  be  taken  up  with  good  appreciation  of  their  origin  and  form. 

Revival  of  the  Old  Rivers.  —  As  soon  as  the  elevation  of 
the  region  began,  the  old  rivers,  .sleepily  wandering  over  the 
peneplain,  were  awakened  to  the  new  task  of  cutting  into  the 
deep  mass  that  had  previously  been  safe  below  baselevel.  Dur- 
ing the  period  of  elevation,  and  ever  since,  they  have  been  busy 
at  this  new  task.    Tli(>  larger  rivers  have  now  cut  their  channels 


286  PHYSICAL   GEOGKAPHY  OF   SOUTHERN   NEW   ENGLAND. 

dowu  to  a  moderate  grade,  and  the  fiirther  deepening  of  their 
valleys  cannot  be  by  a  gi'eat  amount  as  long  as  the  land  stands 
in  its  present  attitude.  The  small  branch  streams  still  have  steep 
courses :  miich  deepening  remains  to  be  done  in  their  valleys. 
During  the  trenching  of  the  valleys  to  their  present  depth,  the 
side  slopes  have  wasted  and  the  valleys  have  widened,  so  that 
they  are  now  nowhere  precipitous.  They  are  not  vertical-sitled, 
like  veiy  young  valleys,  but  have  a  more  adolescent  or  mature 
expression.  The  peneplain  is  no  longer  a  continuous  upland  siu"- 
face,  but  is  thoroughly  carved  into  a  rugged  lull  country.  The 
valleys  are  so  numerous  that  it  requires  a  distinct  mental  effort 
to  recognize  them  as  merely  interruptions  in  the  real  geographical 
unit  of  the  region. 

Depth  and  Breadth  of  the  Valleys. — The  valleys  of  the 
chief  streams  differ  among  themselves  in  two  particulars, — depth 
and  breadth.     They  are  shallow  near  the  coast,  where  the  up- 


FlO.  4.  —  Decrlield  Valley,  above  Shclburne  Falls,  Mass. 

land  is  but  little  above  sea  level;  they  arc  deep  in  the  interior, 
where  the  upland  may  be  a  thousand  or  fifteen  hundred  feet  or 
more  above  sea  level.  Close  to  the  coast,  our  valleys  are  like 
those  of  Florida,  where  hardly  any  depth  of  cutting  is  allowed, 
because  the  whole  State  stands  so  near  the  level  of  the  sea.  In 
the  interior  the  valleys  are  in  nuitter  of  dejtth  related  to  the 


THE    VALLEYS    IN   THE   UPLAND. 


•zsi 


canyons  that  dissect  the  phiteaus  of  Arizona.  In  Itoth  these 
cases  the  considerable  elevation  of  the  upland  gives  the  streams 
permission  to  intrench  tliera selves  pi-ofonndly.  Even  the  Grand 
Canyon  of  tlie  (Jolorado  is  only  about  four  times  as  deep  as  the 
Deerfield  Valley  in  the  view  on  the  preceding  |)age.  The  valley  of 
the  Naugatuck  above  Waterbury,  shown  in  the  iH>xt  figure    ' 


las 


Fui.  0.  —  Naugatuck  Valley,  near  Waterbury,  Conn. 
{Photographed  by  L.  G.  Wcnttjate.) 

a  depth  of  about  five  hundred  feet.  It  sliould  Ix-  noted  that  the 
second  of  these  views,  taken  from  the  level  of  the  upland,  gives 
an  excellent  idea  of  the  relation  of  tlu^  valley  to  the  u])lifted 
peneplain  in  which  it  is  incised,  while  the  pictui-e  of  the  Deertield 
Valley,  taken  from  nearer  the  river  level,  gives  only  i]w  impres- 
sion of  being  inclosed  by  rugged  hills. 

In  respect  to  breadth,  the  most  significant  variation  in  the 
form  of  our  valleys  is  controlknl  by  the  resistance  of  tli(>  rocks  in 
which  they  arc^  worn.  Where  the  rocks  are  of  great  resistance  to 
weathering,  or  Jiinil,  as  we  connnonly  express  it,  the  valleys  are 
stiU  rather  luiri'ow  and  steep-sided ;  and  from  tlus  it  nuist  be 
concluded  that  thei-e  lias  not  yet  been  time  since  the  uplift  of  the 
peneplain  for  valleys  to  widen  greatly  in  rocks  of  this  character. 
But  where  the  I'ocks  weather  rapidly,  or  are  weak  or  ao/t,  as  we 
generally  phrase  it,  the  slopes  to  the  streams  have  already  wasted 
away  so  much  that  the  vaUeys  have  become  A\ide  open.*  The 
upper  and  lower  parts  of  the  Housatoni*  "\''alley  give  excellent 


*JH8  PHYSICAL   GEOGRAPHY    OF    SOTTTHEKN    NEW    ENGLAND. 

illustrations  of  the  contrasted  forms  thus  produced.  The  upper 
valley,  generally  called  the  Berkshire  Valley,  is  broadly  open 
along  a  belt  of  weak  limestones,  which  have  wasted  away  on 
either  side  to  the  hard  rocks  that  inclose  them  on  the  east  and 
west :  the  lower  valley  crosses  the  upland  of  western  Connecticut, 
a  region  chiefly  composed  of  resistant  crystalline  rocks,  and  here 
the  side  slopes  are  for  the  most  part  bold  and  steep.  Indeed, 
here  the  rocks  are  so  resistant  that  the  river  has  not  yet  been 
able  to  cut  down  all  of  its  channel  to  a  smooth  and  gentle  grade. 
In  its  course  of  HT  miles  from  Falls  Village,  where  it  leaves  the 
limestone  belt,  to  Derby,  where  it  meets  tide  water,  this  strong 
stream  descends  560  feet.  It  is  on  account  of  so  great  a  dis- 
tance over  which  the  lower  Housatouic  has  to  cut  its  way  across 
hard  rocks,  that  its  upper  course,  even  on  the  weak  rocks  of  the 
Berkshii-e  Valley,  is  still  held  almost  1,000  feet  above  sea  level. 

Millers  River  offers  another  kind  of  illustration  of  the  general 
principle  by  which  the  breadth  of  our  valleys  is  governed.  Its 
course  leads  westward  near  the  northern  boundary  of  Massachu- 
setts for  about  thirty  miles  to  its  mouth  in  the  Connecticiit.  On 
the  way,  the  river  crosses  successive  belts  of  hardei'  and  weaker 
crystalline  rocks,  trending  about  north  and  south.  Where  the 
rocks  are  weak,  as  between  Athol  and  Oi'ange,  the  valley  is  wide- 
o])ened ;  where  the  rocks  are  hard,  as  above  Athol  and  below 
Orange,  especially  the  latter,  the  valley  is  luueli  narrower. 
Southward  from  Athol,  towards  Brookfield  and  Palmer,  the 
penei)lain  is  much  dissected  by  valleys  that  follow  tln^  belts  of 
weaker  rocks;  and,  instead  of  resembling  a  continuous  jilateau, 
the  upland  consists  of  a  number  of  dissevered  hills.  One  of  the 
sharpest,  most  isolated  of  thes(^  hills  is  seen  just  north  of  Palmer, 
from  the  trains  of  the  Boston  and  .Vlbany  Railroad,  foreshadow- 
ing what  the  rest  of  the  ujiland  nuiy  l)e  reduced  to  when  the 
present  cycle  of  denudation  is  further  advanced. 

East  of  "Woi'cestcM'  ther(^  are  so  many  belts  of  weak  rocks 
that  the  upland  is  greatly  interrupted  ])ybi-oad  valley  lowlands; 
so  much  so,  indeed,  that  the  geogra]iher  wlio  is  just  beginning 
his  outdoor  studies  may  think  that  the  eyes  of  faith  are  needed 
hereabouts  to  recognize  the  upland  remmxnts.  The  lowland  of 
the  Boston  basin  is  one  of  these  broad  interi*uiitions;  Init  along 
its  northern  bord(>r  the  upland  may  be  seen  with  some  distinct- 
ness. •  The  lowland  around  Narragansett  Bay  is  another  and 
even  greater  interruption,  but  the  even  sky  line  of  the  upland  is 


THE   VAi,l.EVh   IN    THE   UPLAND.  289 

e;isily  recognized  on  the  east  and  west.  The  rocks  of  these  low- 
lands are,  indeed,  so  weak  that  they  are  already  almost  reduced 
to  the  present  sea  level,  thus  forming  local  peneplains  of  a  second 
genei'ation.  If  one's  studies  were  limited  to  these  much-denuded 
districts,  it  would  be  very  difficult  to  decipher  their  history ;  but 
coming  upon  them  fi'om  farther  west,  where  the  upland  pene- 
plain is  much  better  preserved,  and  pi-ojecting  its  descending 
plane  into  the  deiuided  districts,  their  relation  to  the  general 
upland  is  perceived  without  difficulty.  No  explanation  of  their 
evolution  seems  so  fitting  as  the  one  here  suggested. 

The  Connecticut  Valley  Lowland.  —  The  finest  of  the  low- 
lands by  which  th(>  upland  is  liroken  is  that  of  the  Connecticut 
Valley.  Hei-e  a  belt  of  weak  I'ed  sandstones  and  shales,  extend- 
ing from  the  northern  border  of  Massachusetts  southward  to 
New  Haven,  has  been  for  the  most  part  worn  down  to  a  rolling 
lowland,  five  or  ten  miles  wide  near  its  extremities,  and  fifteen 
or  eighteen  miles  wide  alnrnt  its  middle.  The  uplifted  peneplain, 
once  evenly  continuous  across  the  sandstone  Ix'lt,  is  now  divided 
by  the  sandstone  trough  into  eastern  and  western  portions,which 
have  nuicli  tlie  aspect  of  rugged  plateaus  when  viewed  from  some 
of  the  occasional  hills  that  surmount  the  vallt\v  lowland.  The 
lowland  has  the  a)>pearance  of  a  long,  deep,  l^i'oatl  ti'ough  when 
seen  from  the  margin  of  the  eastern  or  western  upland. 

Altliough  called  the  Coiuiecticut  Valley,  this  beautiful  low- 
land riuilly  consists  of  the  wide-open  confluent  valleys  of  a  num- 
ber of  streams,  of  which  the  Connecticut  is  the  master.  The 
breadth  of  the  lowland  depends,  not  on  the  size  of  the  Connecti- 
cut, but  on  the  weakness  of  the  rocks  on  which  it  is  opened.  This 
is  particularly  well  shown  l)y  following  the  river  thrcmgh  the  low- 
laud  across  Massachusetts  and  into  tlie  State  of  Connecticut. 
There  the  lowland  continues  southwai-d  to  the  Sound;  but 
tli(!  liver  turns  eastward  at  jNIiddk'town,  and  enters  a  narrow 
valley  in  the  eastern  upland.  Manifestly,  then,  it  is  the  weakness 
of  the  sandstones  and  shales,  and  not  the  size  of  the  Connecticut 
River,  that  has  determined  the  lireadth  of  the  lowland.  There  are 
few  places  when^  this  important  relation  is  better  shown. 

Of  all  the  loc.il  peneplains  of  the  second  generation  in 
New  England,  tlie  Connecticut  Valley  lowland  is  the  best  de- 
veh)ped.  When  viewed  tVom  the  margin  of  tlie  upland,  east  or 
west,  the  smaller  inetiualities  of  its  broad  floor  sink  out  of  sight, 
and  it  seems  to  be  ti-uly  a  jilain  of  completed  denudation.     At 


29U  I'llYSIC.VL   UEOGKAPHY  OF   SOl'THEKX    XEW    ENGL.\ND. 

the  noi-tlieru  border  of  Couuecticut,  where  the  iiphiuds  have  a 
height  of  about  eight  huiub-ed  feet,  the  lowbiiid  liardly  averages 
a  hundred  feet  above  the  !<ea.  Near  the  uortheru  border  of 
Massachusetts  the  uphuids  rise  to  twelve  or  fom-teeu  huudi-eil 
feet,  but  the  lowlaud  hardly  reaches  two  hundred  feet.  One  of 
the  most  important  lessons  to  be  learned  from  this  is  the 
remarkable  contrast  in  the  rate  of  weathering  and  wasting  of 
the  crystalline  rocks  that  still  retain  the  upland  fonm,  and  of 
the  red  sandstones  and  shales  which  are  already  worn  down  to 
a  lowland.  Hand  specimens  of  the  two  kinds  of  rook  readily 
declare  a  difference  in  their  hardness.  The  stonecutters  who 
di-ess  the  blocks  of  Monson  gneiss  and  Lougmeadow  sandstone, 
so  often  used  in  architectural  combination  in  recent  years,  will 
testify  emphatically  as  to  which  rock  is  the  more  resistant ;  yet 
it  woidd  hardly  be  expected,  after  the  most  careful  artificial 
tests,  that  the  long-continued  natural  test  of  weathering  Avould 
have  discovered  so  gi-eat  a  contrast  in  resistance  as  is  indicated 
by  the  foi-m  of  the  areas  occupied  by  the  two  rocks.  One  stiU 
stands  boldly  up  close  to  the  height  which  both  gained  when  the 
peneplain  was  uplifted,  but  from  which  the  other  has,  as  it  were, 
melted  away  under  the  rays  of  the  sun. 

The  same  lesson  is  enforced  when  the  observer  stands  on  one 
of  the  upland  hills  near  Middletown,  and  sees  on  the  west  the 
broad  valley  lowland,  and  on  the  southeast  the  steep-sided  valley 
through  which  the  lowland  is  drained.  While  the  narrow  outlet 
valley  of  the  Connecticut  has  opened  by  wasting  in  the  hard  rock 
area  only  to  its  present  restricted  breadth,  all  the  extensive 
valley  lowland  has  been  worn  out.  With  the  exception  of  the 
small  pai't  of  the  lowland  that  discharges  to  the  Sound  at 
New  Haven,  all  the  rock  waste  from  the  broad  belt  of  sand- 
stones and  shales  has  been  carried  down  the  narrow  valley  to  the 
sea.  This  is  the  best  example  in  New  England  of  the  general  re- 
hition  between  open  longitudinal  and  narrow  transverse  valleys. 
The  uatiiral  prepossession  in  such  a  case  is  that  the  broad  valley 
lowland  is  older  than  the  narrow  outlet  valley;  and  hence  arise 
the  mistaken  explanations  of  tlie  outlet  as  a  "fracture  due  to 
some  con^'ulsion  of  nature,"  or  as  the  "channel  carved  by  the 
overflow  of  a  lake  "  that  is  conveniently  assumed  to  have  for  a 
time  filled  the  lowland.  These  eiToneous  ideas  have  a  wide 
acceptance  among  teacliers  at  present,  although  there  is  no 
shadow  of  e\'idence  to  support  them  in  such  an  example  as  the 


THE   VALLEYS   IN   THE    UPLAND.  291 

one  here  under  discussion.  It  is  true  that  the  bi'oad  lowland  is 
older  than  the  narrow  outlet  valley  iu  topogi-aphic  expression, 
but  they  are  of  the  same  absolute  age,  measured  in  centuries. 
The  lowland  was  not  made  before  the  outlet,  but  only  at  equal 
jiace  with  it.  Both  are  excavations  in  the  uplifted  peneplain. 
The  excavation  of  both  began  at  the  tinu^  of  the  uplift.  The 
deepening  of  the  downstream  outlet  controlled  tlie  deepening  of 
the  upstream  lowland;  for  tliis  relation  always  obtains  between 
the  downstream  and  the  upstream  portions  of  a  river.  It  is  in 
breadth,  not  in  age  or  dejyth,  tliat  the  valley  lowland  and  the 
outlet  valley  are  unlike,  and  it  is  plain  that  the  matter  of  breadth 
is  entirely  controlled  by  the  nature  of  the  rocks  in  which  the 
valleys  are  excavated.  "With  so  excellent  an  illustration  of  this 
principle  as  the  Connecticut  affords,  it  is  to  be  hoped  that  its  true 
explanation  may  soon  be  introduced  iu  our  elementary  teaching. 

The  relation  of  the  longitudinal  and  transverse  valleys  is 
shown  again  in  the  long  Berkshire  limestone  valley  and  its  trans- 
verse outlet  by  the  lower  Housatouic,  as  already  mentioned; 
but  this  is  less  conspicuous  than  the  case  of  the  Connecticut. 
The  latter  is,  howevei',  overshadowed  Ijy  the  Hudson,  which 
drains  a  part  of  the  great  Aitpalachian  Valley  through  the  deep 
gorge  in  the  Highlands.  The  same  relation  is  exhibited  by  the 
Delaware,  the  Susquehanna,  the  Potomac,  and  tlie  James,  as  well 
as  by  innumerable  smaller  Appalachian  streams,  that  drain  open 
inner  longitudinal  vaUeys  through  narrow  transverse  gorgt^s  oi- 
iratcr  (/(tps.  All  the  rock  waste  of  the  open  inner  valleys  has 
been  carried  out  through  the  narrow  gorg(»s.  Nothing  less  than 
the  sight  of  one  of  these  examples  will  do  justice  to  the  impoi'- 
tant  lesson  that  they  teach. 

The  Lava  Ridges  of  the  Connecticut  Valley  Lowland. — 
Recall  for  a  moment  the  Monaduocks  that  stand  over  the  uplands 
like  monuments  of  dej^ai'ted  mountains.  Their  occurrence  should 
lead  us  to  expect  that  residual  eminences  might  occur  on  the  local 
peneplains  of  the  second  generation.  Such  younger  Monaduocks 
are,  in  fact,  a])undant.  The  Boston  basin  counts  them  by  the 
score,  especially  in  the  area  of  the  Roxbury  pudding  stone ;  but 
the  best  examples  of  these  residuals  occur  within  the  Connecti- 
cut Valley  lowland,  aud  some  of  these  are  of  particular  interest 
from  their  relation  to  the  ancient  volcanic  history  of  the  region. 

Long  ago — long  before  the  peneplain  of  to-day  was  made, 
uplifted,  and  dissected — the  red  sandstones  and  shales  were  ac- 


292  PHYSICAL.  GEOGKAPHY   OF  SOUTHERN   NEW   ENGLAND. 

cumulated  in  a  trough  or  estuary  between  eastern  and  western 
highlands.  It  was  during  the  deposition  of  these  strata  that  the 
famous  "  bird  tracks  "  —  really  rei)tilian  tracks  —  were  made  upon 
successive  layers  of  mudtly  sand.  The  museum  of  Amherst 
College  contains  an  extraordinary  collection  of  them.  For  the 
geographer,  the  floods  of  lava  or  trap  that  were  at  several  times 
poui-ed  out  over  the  sandstone  strata,  and  afterwards  buried  by 
later  deposits,  are  more  important.  The  molten  lava  spread  over 
the  even  floor  of  th(^  muddy  estuary  in  broad  sheets,  many  miles 
in  length  and  breadth,  and  from  one  to  four  hundred  feet  in 
thickness.  Some  dikes  and  sheets  of  lava  were  diiven  in  among 
the  sandstone  beneath  the  surface.  At  last  the  further  accumu- 
lation of  deposits  in  the  estuary  was  stopped  by  the  distiirbance 
that  gave  the  peculiai'  tilted  and  broken  structure  to  the  belt  of 
red  sandstones ;  and  then  it  was  that  long-continued  denudation 
produced  the  penei)lain  that  has  been  our  chief  theme,  leveling 
otE  the  crystalliue  highlands  east  and  west,  as  well  as  the  up- 
turned and  dislocated  blocks  of  sandstones,  .shales,  and  lavas.  It 
would  requii-e  a  special  monograph  to  do  justice  to  the  particular 
structures  of  this  interesting  region.  Let  it  now  suffice  to  restore 
the  picture  of  the  evenly  denuded  surface  of  the  sandstone  belt 
as  a  part  of  the  old  peneplain  between  the  less  smoothly  denuded 
areas  of  crystalline  rocks  on  the  east  and  west.  The  sandstone 
beds  generally  dip  underground  eastward,  and  among  them  are 
the  various  sheets  of  lava,  much  dislocated.  Now,  when  the  fur- 
ther smoothing  of  the  peneplain  was  stopped  by  the  slanting  up- 
lift of  the  region,the  sandstones  and  shales  wasted  away  with  com- 
parative rapidity ;  but  the  trap  sheets  and  dikes  resisted  erosion 
strongly,  and  soon  came  to  have  a  distinct  relief  above  the  wast- 
ing sedimentarj-  beds.  Even  when  the  latter  are  reduced  to  the 
open  lowland  form  that  they  have  to-day,  the  hea^-ier  sheets  and 
thicker  dikes  of  trap  retain  a  great  part  of  the  height  to  which 
they  wei'e  uplifted,  thus  simulating  the  behavior  of  the  hard 
gneisses  and  schists  of  the  upland. 

As  the  lava  sheets  dip  eastward  with  the  sandstones,  the 
western  face  of  the  ridges  exposes  bold  outcropping  ledges,  de- 
scending precipitously  to  long  talus  slopes  of  loose  rocky  waste, 
which  covers  the  underlying  sandstone  beds ;  while  the  eastern 
or  back  slope  of  the  ridges  descends  more  gradually  with  the 
slant  of  the  lava  sheets,  and  the  next  overlying  sandstone  beds 
are  found  only  near  the  foot  of  the  slope.     Mount  Tom,  near 


0 


THE   VALLEYS   IN    THE   UPLAND. 


293 


Nortliaiupton,  Mass.,  and  the  Hanging  Hills,  noai-  Meriden,  Conn., 
are  among  the  finest  examples  of  these  trap  ridges.  From  their 
summits  one  may  look  evenly  aei-oss  to  the  njilands  on  th(^  east 
and  west,  appreciating  the  plateau-likci  sniootliiicss  of  their  hill- 
tops; one  may  survey  the  broad  valley  lowland  beneath,  with  its 
patchwork  of  field  and  woodland,  and  its  mnny  villages.    Various 


KiG.  G. 


-South    M()Uiit:iiii,  Ilaiii^iiiK  Jlills.  MciicU'ii,  ('(inn. 
{Photographed  by  W.H.  C.  Pyiichon.) 


other  ridges  belong  to  the  same  range,  and  ai*e,  indeed,  the  out- 
cropping edges  of  tiie  same  lava  sheet;  the  various  notches  oi- 
gaps  by  whi(!h  the  individual  mountains  are  separated  being  due 
to  dislocations  of  the  sheet  made  at  the  time  when  the  sandstones 
and  the  included  lava  beils  were  tilted.  Mount  Holyoko  and 
Mount  Tom,  on  th(^  north;  Talcott  Mountiiin,  west  of  llar1foi-d; 
the  Hanging  Hills,  Lamentation  and  Higby  mountains,  near  ^leri- 
den;  and  Totokct  nnd  P(Uid  (Saltonstall)  mountains,  east  of  New 
Haven,  —  are  conspicuous  meiidx'rs  of  tlie  scries,  and  are  all 
parts  of  a  singlt^  lava  bed. 

East  and  West  rocks,  near  New  Haven,  and  the  lon.<r  north- 
ern continuation  of  the  latter  to  (lavloi-d  Mountain,  are  tlie  chief 


294  PHYSICAL   GEOGRAPHY   OF   SOUTHERN    NEW   ENGLAND. 

examples  of  ridges  formed  on  intrusive  lava  sheets ;  these  ha\dng 
been  driven  in  between  the  sandstone  beds,  instead  of  being 
poiu-ed  out  over  their  snrface.  Monnt  C'ai'mel  and  the  Blue  Hills, 
soutliwest  of  Wallingford,  have  a  peculiar  interest  from  marking 
the  site  of  great  dikes  or  iiccl's  of  lava.  In  all  probaViility  they 
are  the  roots  of  the  volcano  or  volcanoes  from  whicli  the  lava 
sheets  of  the  Meriden  district  were  erupted.  Similar  but  smaller 
necks  have  been  found  on  the  southern  side  of  Mount  Holyoke 
range  in  Massachusetts.  Occasionally  the  lowland  is  surmounted 
by  ridges  of  resistant  sandstone  (as  Deerfield  Mountain  and  the 
Sugar  Loaves,  above  Northampton)  or  of  conglomerate  (as  Mount 
Tob}%  north  of  Amherst),  but  these  are  seldom  conspicuous. 

The  Berkshire  VaUey  is  also  varied  bj^  a  number  of  isolated 
hills  or  mountains.  Here  they  consist  of  resistant  schists  that 
stand  above  the  limestone  floor.  Greylock  is  the  chief  of  these ; 
for  its  summit  not  only  lises  above  the  Berkshire  VaUey,  but 
dominates  the  upland  levels  on  the  east  and  west  as  well,  reach- 
ing the  greatest  altitude  of  any  mountain  in  Massachusetts. 
Smaller  and  lower  residuals  are  seen  soutli  of  Pittsfield,  where 
they  contriljiite  largely  to  the  attraction  of  the  picturesque  dis- 
trict about  Stockbridge  and  Great  Barrington.  Bear  Mountain, 
in  the.extreme  northwestern  part  of  Connecticut,  the  highest  sum- 
mit in  the  State,  may  be,  for  oiu-  purposes,  hkened  to  Greylock. 

On  any  of  the  higher  trap  ridges  in  the  Connecticut  Valley, 
the  lesson  of  rapid  and  slow  wasting  of  weak  and  hard  rocks  may 
be  reviewed  to  advantage.  The  meaning  of  the  geogi-aphical 
forms  there  tlisplayed  gradually  becomes  so  distinct  that  we 
need  not  say,  "  The  lava  sheets  are  harder  than  the  sandstones, 
and  hence  the  lava  stands  up  in  ridges,  while  the  sandstones 
have  been  worn  down  to  a  lowland,"  but,  "  The  lava  sheets  stand 
up  in  ridges,  while  the  sandstones  occupy  the  lowland :  hence  the 
lava  must  be  much  harder  than  the  sandstones."  The  ridges  do 
not  owe  their  height  alcove  the  lowland  to  any  local  uplift,  but 
simply  to  retaining,  in  virtue  of  their  hardness,  much  of  the 
li eight  which  the  weaker  sandstones  have  lost.  ^Vhere  relations 
of  this  sort  are  clearly  ajijireciated  by  geographers,  it  will  require 
no  argument  to  i)ersuadc  them  that  the  processes  and  results  of 
land  sculpture  should  form  an  essential  part  of  geographical 
training. 

Distribution  of  Population. — It  has  already  been  stated 
that  the  valleys  and  lowlands  are  the  seats  of  the  greatest  part 


THE  VALLEYS  IN  THE  UPLAND.  295 

of  our  population,  while  the  uplands  are  sparsely  occupied.  The 
full  reason  for  this  wiU  not  be  perceived  until  the  relation  of 

valleys  to  bays  and  harbors,  and  the  origin  of  the  watcn-  i)owers 
of  the  valley  streams,  are  explained;  but  the  broad  fact  is  easily 
appreciated.  Look,  for  example,  at  the  western  upland  in  con- 
trast with  tlic  Berkshire  and  the  Connecticut  valleys  west  and 
east  of  it.  On  the  upland  itself  there  are  quiet,  out-of-the-way 
hUl  towns,  like  Savoy,  Florida,  Peru,  Monterey.  It  is  through 
these  hill  towns  that  the  pedestrian  should  plan  his  excursion,  if 
he  would  escai)e  from  the  ))ustle  of  the  world  heueatli,  and  find 
still  preserved  the  quiet  old  New  England  ways.  It  is  a  district 
of  smaU-field  farming,  too  rugged  for  general  cultivation.  The 
patches  of  timber  land  sup])ly  wood  for  small  local  industries  in 
the  villages,  and  i>ulp  for  jiaper  mills  in  the  valleys;  ])ut  to  gain 
a  living  there  is  harder  work  than  New  Englanders  even  have 
cared  to  face,  and  they  have  either  descended  to  the  gi'owing 
manufacturing  towns  at  lower  levels,  or  they  have  moved  out 
West  to  prairies  and  plains.  Abandoned  fannhouses  on  the  side 
roads  tell  the  story  with  sometliing  of  a  dreary  intonation,  —  the 
garden  patches  lost  in  wee<ls,  the  apple  orchards  gone  to  waste, 
the  pasture  lots  overgrown  with  bushes  and  briers. 

The  narrow  valleys  within  the  upland  have  thriving  vUlages, 
connected  with  the  rest  of  the  world  by  railroad  lines.  Here  the 
farmers  from  the  upland  come  down  to  trade ;  here  manufactur- 
ing industiies  are  established  in  great  varietj% — cutlery  works 
and  shoe-peg  shojis  at  Shellnirne  Falls  in  the  Deerfield  Valley, 
emery  works  at  Chester  in  the  Westfield  Valley;  while  nearer 
the  great  market  of  New  York  City,  along  the  Farmington  and 
Naugatuck  valleys  in  the  western  upland  of  Connecticut,  hard- 
ware, tools,  clocks  and  watches,  and  lirass  goods  of  every  de- 
scription, are  produced.  It  would  lead  into  the  d(>batable  ground 
between  geography  and  history  to  recount  the  causes  that  have  de- 
termined the  growth  of  these  manifold  industri(>s.  Suffice  it  for 
the  present  to  note  that  they  arc  strictly  limited  to  the  valleys. 

Emerging  from  the  nai-row  valleys  to  the  more  open  valleys, 
we  find,  on  the  west.  North  Adams,  with  cotton  and  woolen 
mills,  and  boot  and  shoe  shops;  Williamstown,  with  its  college; 
Pittsfield,  with  varied  manufactures  and  an  active  trade  with  the 
surrounding  agricultural  region ;  Dalton  and  Hinsdale,  witli  great 
paper  mills,  in  a  side  valley  descending  from  the  liills  on  the  east 
side  of  the  limestone  belt.     On  the  eastern  side  of  the  Berkshire 


29G    PHYSICAL  GEOGRAPHY  OF  SOUTHERN  NEW  ENGLAND: 

phitenu  the  contrast  is  much  strouger  between  the  rugged  uphmd 
and  oi)eu  lowland ;  for  the  Connecticut  Valley  lowland  is  longer, 
broader,  and  lower  than  the  Berkshire  \'alley.  Its  smooth  fields 
tempted  early  settlement  from  the  Colony  of  Massachusetts  Bay. 
Many  populous  cities  and  towns  are  built  upon  it;  railroads 
traverse  it  lengthwise  and  crosswise;  manufactures  tlirive; 
schools  and  colleges  not  only  educate  the  youth  of  the  valley, 
but  attract  boys  ;iud  girls  from  the  upland,  and  young  men  and 
young  women  from  all  over  the  country;  products  suggestive  of 
a  mild  climate,  such  as  tobacco  and  jteaches,  come  from  the 
valley  farms ;  garden  seeds  are  raised  as  an  important  article  of 
trade.  And  nil  tlie  uulikeness  of  the  lowhmd  to  the  uphmd  is 
because  the  rocks  of  the  one  have  wasted  away,  while  those  of 
the  other  have,  comparatively  speaking,  lield  fast.  This  is  the 
imin-essive  lesson  of  the  dependence  of  the  manner  of  life  on  the 
sculpture  of  the  land,  that  our  geographies  should  teach. 

Near  the  coast,  where  the  contrast  between  uj>land  and  low- 
laud  is  less  market!  than  in  the  interior,  the  control  exercised  by 
the  form  of  the  land  on  the  distriVmtion  of  pojmlation  and  in- 
dustries is  not  so  striking  as  farther  inland,  but  it  may  genendly 
be  perceived  in  a  gi'eater  or  less  degree.  Nearly  all  the  suburban 
(.'ities  and  towns  around  Boston  are  on  the  floor  of  the  basin. 
Tlie  upland  of  the  Middlesex  Fells  and  the  Monadnock-like 
Blue  Hills  are  reserved  as  Avooded  public  parks.  The  numerous 
mauiifacturing  A-illages  of  eastern  Massacliusetts  and  of  Khode 
Island  are  on  comparatively  low  ground;  Marlboro  and  Spencer 
(shoe  towns),  and  (birdner  and  Templeton  (cluur  towns),  being 
almost  the  only  exceptions  to  tliis  prevailing  rule. 

REVIEW. 

A  paragrajih  may  be  given  to  reviewing  what  has  been  thus 
far  exi>laine(l.  The  upland  of  soutliern  New  England  serves  us 
as  the  type  of  a  peneplain,  now  ui>lifted  and  well  advanced  in  n 
second  cycle  of  denudation.  Monadnock  is  a  standard  example 
of  a  residual  mountain  that  rose  aliove  the  peneplain  when  it 
was  still  a  lowland,  and  tliat  continues  to  dominate  the  i)enei>lain 
now  that  it  has  become  an  upland.  The  Deerfield  Valley  exiiil>i1s 
a  moderate  advance  of  the  processes  of  dissection  that  will  in 
time  reduce  even  the  hard-rock  u])land  to  a  lowland.  The  Con- 
necticut Valley  lowland  is  a  typical  example  of  a  local  peneiilain 


itEViEW.  297 

of  the  secoiul  generatiou,  already  developed  on  a  belt  of  weak 
rocks,  and  inclosed  by  the  adjoining  hard-rock  upland.  Mount 
Tom  is  an  admirable  illustration  of  a  residual  mountain  of  the 
second  generation,  bearing  the  sanie  relation  to  tlie  valley  lowland 
as  that  which  Mouadnoek  bears  to  the  general  upland.  In  Vir- 
ginia, residual  nioiintains  of  this  later  generation  liave  been  called 
( '<if(>cti)/.s,  taking  the  name  of  one  of  them  to  rejn-esent  the  class ; 
and  when  our  isolated  hills  come  to  be  recognized  as  remnants 
surmounting  the  earlier  or  the  later  peneplain,  the  two  terras 
Moiiadiiocl-s  and  Catocfii/s  may  be  eni]>loyed  to  designate  tlie 
members  of  the  older  and  younger  families. 

Another  ])aragraph  may  be  allowed  to  cautioning  the  reader 
against  forming  too  i-igid  and  artifrcial  conceptions  of  the  natural 
processes  liere  referred  to.  It  must  not  ])e  thought  that  tiie  land 
stood  absolutelj'  still  during  all  the  long  period  of  ei'osion 
by  which  the  peneplain  of  the  uplands  was  produced.  Many 
oscillations  of  level  probably  took  ])lace,  during  which  erosion 
was  hastened  or  retarded.  All  tliat  the  occurrence  of  the  pene- 
plain demands  is,  that  the  oscillations  of  level  were  not  of  great 
measure,  and  tliat  the  average  stand  of  the  land  remained  close 
to  the  level  of  tlie  i)eneplain  for  a  long  time.  Again,  it  nnist 
not  be  tliought  that  the  erosion,  by  which  the  very  ancient 
iriountains  were  laid  low  and  tlie  peneplain  of  the  upland  was 
produced,  was  all  accoini)lishe<l  dining  one  uninterrupted  <'ycle 
of  destructive  work.  Diu-ing  the  wasting  of  the  ancient  moun- 
tains, the  land  may  have  had  several  successive  cycles  of  erosion, 
sepai'ated  by  tiplifts  and  deformations  of  greater  or  less  value. 
In  each  of  these  cycles  the  surface  of  tlie  land  Iiiay  liave  l)een 
worn  down  more  or  less  completely  to  the  appropriate  baselevel. 
Hence  we  are  probably  in  error  when  speaking  of  the  local  ]»ene- 
plains  of  the  vaUey  lowlands  as  belonging  to  a  srcoinl  genei'ation, 
and  tlms  inii)lying  that  the  peneplain  of  the  upland  was  of  the 
first  generation.  The  upland  i)eneplain  is  truly  the  oldest  tliat 
has  j'et  been  clearly  recognized  ;  but  perhaps,  when  the  sctdpture 
of  tlie  Wliite  ^Mountains  and  of  the  Adirondacks  is  carefully 
studied,  still  older  iiiid  higher  peneplains  may  be  discovered,  as 
the.v  have  already  lu'cn  in  the  highlands  of  Nortli  Carolina. 
Caution  would  therefore  suggest  tiiat  tlie  peneplain  of  our  ujiland 
be  referred  to,  in  algebraic  tertns,  as  of  the  vi\\  generation  :  \\w 
local  peneplain  of  the  lowlands  would  then  l)e  of  tlie  {n  H-  l)th 
generation.     Still   further,   it  nnist   not   be  imagintul  that   the 


298  PHYSICAL  GEOGllAPHY   OF   SOUTH  EUN   NEW   ENGLAND. 

gi-eater  deformation  liy  which  the  aiicieut  mouutairis  were  pro- 
duced was  the  result  of  a  single  period  of  disturhance:  various 
successive  eiforts  of  crushing  and  hreaking  tlie  ci'ust  of  the  earth 
jirobably  occurred,  and  at  some  iiiulctiiicd  time  between  the  first 
crushing  and  final  weanng  down  to  the  i)eueplain  level  the 
ancient  mountains  gained  tlieir  greatest  height.  It  may  be 
noted,  however,  that  the  latest  serious  deformation  of  the 
New  England  region  was  the  one  by  which  the  sandstones  and 
lava  sheets  of  tlic  Connecticut  Valley  belt  were  tilted  and  broken. 
The  slanting  uplift  of  the  peneplain  to  the  upland  altitude  seems 
to  have  been  accomi)lished  without  pei'ceptible  breaking,  and 
with  only  a  slight  warping. 

THE   GLACIAL   INVASION. 

The  liujits  of  this  monograpli  prevent  more  than  a  brief  con- 
.sideration  of  two  remaining  subjects, — the  glacial  invasion,  by 
means  of  which  many  characteristic  geographical  details  were  de- 
termined; and  the  associated  depression  of  the  land,  as  a  result 
of  which  the  lower  parts  of  many  valleys  were  changed  into  bays. 
Hence  we  nuist  proceed  more  rapidly  to  direct  assertion. 

Vakious  Forms  assumed  by  Glacial  Drift. — Just  as  Green- 
land is  now  ice-covered,  so  was  New  England  once  ice-covered 
after  the  general  features  of  upland  and  valley  liad  been  de- 
veloped. The  ice  sheet  was  thick  enough  to  bury  our  Monad- 
nocks.  It  crept  slowly  down  the  general  sloj)e  of  the  upland  to 
the  south  and  southeast;  it  scraped  along  all  tlie  loose  soil  that 
it  found  ready  made,  it  plucked  many  a  bowdder  from  projecting 
ledges,  and  it  wore  down  the  rock  surface  somewhat  lower  than 
it  had  been;  it  was  jn'csumably  more  active  in  deepening  the 
soft-rock  valleys  than  in  rubl)ing  down  the  hai'd-i-ock  hills.  If 
the  ice  sheet  had  lasted  a  very  long  time,  or  acted  with  very 
gi-eat  energy,  it  might  have  left  the  rocky  floor  of  New  England 
clean-swept  and  bare ;  but  as  a  fact  the  greater  ])art  of  the 
plunder  that  it  had  gathered  was  dragged  along  for  only  a 
moderate  distance,  and  now  lies  spread  irregularly  over  our 
province  as  a  sheet  of  drift.  The  lowest  mendjer  of  the  drift, 
lying  directly  on  the  scored  rock  surface,  is  an  unstratified,  com- 
pact mixture  of  all  manner  of  materials,  coarse  and  fine ;  this  is 
called  hon-hJpr  clai/  or  till.  Its  surface  is  generally  smoothly  roll- 
ing.    Here  bare  ledges  i)rotrude  thiough  it;  there  its  thickness 


THE   GLACIAL  INVASION. 


2!»!» 


locally  increases,  so  that  it  assumes  the  form  of  rouuded  hills, 
called  drumlins,  averaging  half  a  mile  in  length  and  toward  two 
hundred  feet  in  height.  Many  of  these  may  bo  seen  on  the  up- 
land between  Speucer,  Mass.,  and  Pomfret,  Conn.  They  occur 
in  lowlands  also,  as  on  the  floor  of  Boston  basin  and  on  the  Con- 
necticut Valley  lowland  about  Dui'ham.  So  inuch  of  the  drift  as 
was  dragged,  carried,  or  washed  along  to  the  fartliest  margin  of 
the  ico  sheet  formed  there  a  aeries  of  uneven  liills  inclosing  manv 


Fig.  7.  —  l)i'umliii,  Grotuu,  Muss. 
(Photoijraphcd  by  G.  £f.  Barton.) 

an  undrained  hollow  among  them,  and  fronted  by  a  plain  of 
washed  sand  and  gravel  spread  forward  by  the  escai)ing  ice 
water.  Ilill  i-aiiges  of  this  kind  are  called  fcrwiiial  moraines. 
lihode  Island  ^jossesses  an  excellent  exanii)lc  near  its  southern 
coast,  west  of  Point  Judith.  Southward  from  Plymouth,  Mass., 
morainic  hills  may  be  traced  far  around  the  cui've  of  Cape  Cod. 
As  the  ice  sheet  was  hually  melting  away,  much  gravel,  sand, 
and  clay  were  washed  forward  from  its  irregularly  r(>treating 
edge,  and  lodged  in  valleys  and  lowlands,  sometimes  taking  the 
shape  of  gravel  ridges,  formed  in  tunnels  under  tiie  ict^  near  its 
margin,  and  then  named  cskcrs,  like  the  so-called"  Indian  Ridges" 
at  Andover,  Mass. ;  sometimes  accumulating  in  sand  and  gravel 
mounds,  formed  in  cavities  close  to  the  ice  edge,  and  then  called 


300  PHYSICAL   GEOGIUPHY   OF   SOUTHEUN    NEW    ENGLAND. 

kames ;  sometimes  spread  out  in  smooth  flood  plains,  especially 
along  the  lai-gev  stream  courses,  but  now  partly  washed  away, 
and  thus  forming  our  well-known  r'tvei-  terraces.  The  irregular 
distribution  of  tlie  drift  has  obstructed  mauy  valleys,  and  thus 
formed  our  numerous  lakes  and  ponds.  The  streams,  more  or  less 
displaced  from  tlicir  well-graded  channels  of  i»reglacial  time,  have 
here  and  there  cut  down  through  the  drift  upon  buried  rock 
ledges ;  and  thus  our  rapids  and  fallfe  have  been  produced. 

GrEOGEAPHICAL  CONSEQUENCES  OF  GlACL\E  AcTION.  —  Although 

strictly  su])ordinate  to  the  stronger  features  of  uplands,  valleys, 
and  lowlands,  it  is  manifest  that  all  these  minor  drift  forms  are 
important  as  geogi'aphical  details,  and  as  such  they  should  have 
due  consideration  in  our  home  teacliing.  Glacial  action  had  no 
share  in  the  evolution  of  Florida  and  Texas,  and  it  would  there- 
fore^ be  a  comparatively  irrelevant  subject  in  Southei'n  schools ; 
but  in  New  England,  glacial  action  has  been  a  more  important 
factor  in  our  geographical  development  than  the  Indians  ever 
were  in  our  historical  development.  The  glacial  elements  in  our 
geography  have  distinctly  affe(?ted  the  course  of  our  history  from 
beginning  to  end,  while  the  Indians  were  after  a  time  pushed 
aside.  The  hills  that  guided  the  Pilgrims  fi-om  Proviucetown 
across  Cape  Cod  Bay  to  Plymouth  were  the  moraines  of  Manomet. 
The  broad  drift  plains  of  the  Connecticut  were  early  sought  out 
as  places  for  settlement  when  the  rugged  uplands  that  sepa- 
rated them  from  the  colonies  of  the  eastern  coast  remained  a 
wilderness;  tlie  many  "fields" — Springfield,  Northfield,  West- 
li(4d,  Greenfield,  Decrfield,  and  tlie  rest — all  owe  their  surnames 
to  the  smooth  drift  floor  of  the  vaUey  lowland.  Tlie  last  battle 
of  King  Philip's  war  was  fought  in  the  mai'shy  district  to  which 
the  Indians  had  retreated  behind  the  terminal  moraine  of  south- 
ern Rhode  Island.  Tlie  small  smelting  furnaces  in  wliicli  iron 
was  made  in  New  England  1)efore  the  daj's  of  railroads,  were 
supplied  with  bog  ore  that  was  taken  from  shallow  glacial  ponds 
or  marshes.  The  lakes  that  often  serve  as  reservoirs — to  flood 
streams  and  wash  logs  down  to  the  mills,  to  store  water  for  fac- 
tories, and  to  supply  water  to  cities  and  towns — are  all  of  glacial 
origin.  Beacon  Hill,  Bunker  Hill,  and  the  hiUs  of  Somerville,  on 
which  earthworks  were  thrown  up  during  the  Revolutionary 
sti-uggle  about  Boston,  are  all  drumlins.  The  plentiful  supply  of 
sand  and  gravel  that  has  made  the  filling  of  Boston  Back  Bay 
comparatively  inexpensive  has  all  come  from  kames  and  sand 


THE  COAST  LINE.  301 

I)lains  a  few  miles  up  the  valley  of  the  Charles  River.  The 
water  power  around  which  so  uiueh  New  England  capital  has 
been  invested,  and  about  which  so  large  a  share  of  New  England 
population  is  gathering,  is  all  a  consequence  of  the  glacial  inva- 
sion ;  and,  although  steam  has  in  recent  years  been  largely  added 
to  water  power,  it  remains  true  that  the  beginning  of  the  gi'eat 
industries  of  Fall  River,  Lowell,  Manchester,  Lewiston,  Paw- 
tucket,  Waterbury,  and  many  other  places,  depended  strictly  on 
the  falls  ill  the  streams  on  which  these  striving  cities  were  Ijuilt. 
The  occurrence  of  waterfalls  not  only  in  the  small  head-water 
streams,  but  also  on  the  lower  courses  of  the  larger  rivers,  is 
peculiarly  characteristic  of  their  origin,  and  peculiai-ly  important 
in  their  economic  relations;  for  thereby  the  factory  towns  and 
cities  often  gain  lai'ge  volumes  of  water  in  the  fall,  combined 
with  situation  not  far  inland. 

THE   COAST   LINE. 

The  Uepkession  of  the  Land.  —  When  our  valleys  are  fol- 
lowed down  to  the  sea,  we  find  no  deltas  built  forward  by  the 
streams,  in  spite  of  the  large  amount  of  rock  waste  that  has 
been  washed  out  from  the  upland  during  its  dissection.  On  the 
contrary,  before  the  general  shore  line  is  reached,  the  broadening 
floor  of  the  valley  is  flooded  with  tide  water,  and  the  running 
river  is  transformed  into  an  estvuiry  or  a  bay.  The  simplest 
explanation  of  all  this  is,  that,  since  the  valleys  were  excavated, 
the  region  has  svift'ered  a  moderate  depression,  whereby  the  up- 
land margin  is  sunk  below  sea  level,  its  outer  hills  standing  up 
"half-seas  over"  as  islands,  while  the  lower  ends  of  its  valleys 
are  drowtied.  The  estuary  of  the  Thames  below  Norwich,  Conn., 
is  as  beautiful  an  exainple  of  a  drowned  valley  as  can  be  found 
anywhere;  it  shovfld  serve;  New  Englanders  for  a  type  of  the 
many  other  examples  of  the  kind  elsewhere  in  the  world. 
Narragansett  Bay  is  but  the  submerged  i)art  of  a  lowland  that 
is  otlun'wise  in  many  ways  comparable  to  the  Connecticut  Valley 
lowland.  The  tliree  rivers,  Pawtux(>t,  Blackstone,  and  Taunton, 
that  once  were  only  branches  of  what  may  be  called  "  Narragan- 
sett River,"  are  now  converted  into  inch^pendent  river  systems 
by  the  drowning  of  their  truidv;  and  here  again  we  have  a  type 
example,  in  terms  of  which  many  cases  in  foreign  lands  may  be 
easdy  described.    The  fringing  islands  along  the  coast  of  Maine 


30*J  I'HYSICAL   GEOaRATHY   OF   SOLTHEKX    NKW    EN(iLAXl). 

are  the  half-dvowiied  hills  that  once  surmounted  tlie  intervening 
valley  flooi-s,  the  latter  being  now  submerged  by  long  arms  of 
tilt'  sea.  Norway  and  Patagonia  are  best  tauglit  after  these  home 
illustrations  are  appreciat^'d. 

Modification  by  'WA^T.s  and  Curuexts.  —  Since  the  land  and 
sea  assumed  their  present  relative  position,  the  waves  and  the 
tides  have  effected  certain  signiticant  changes  in  the  form  of  the 
coast ;  and  here  we  enter  upon  a  subject  that  deserves  as  delib- 
erate a  treatment  as  has  been  given  to  our  dissected  peneplain. 
In  a  general  way  the  changes  along  the  sliore  tend  to  promote 
simplicity  of  outline :  the  islands  are  in  time  cut  away  ;  the  head- 
lands are  cut  back ;  and  the  bays  are  l)ridged  across  with  bars, 
and  filled  with  deltas  and  tidal  marshes.  Given  time  enough, 
and  the  irregular  margin  of  New  England  woidd  be  cut  back 
into  long,  smooth  curves,  like  those  of  northwestern  France, 
where  the  sea  has  made  great  inroads  on  the  land;  but  time 
enough  has  not  yet  been  allowed.  ^Tiere  oiir  coast  is  rocky,  it 
has  not  as  yet  suffered  much  change :  the  resistant  headlands  are 
not  yet  cut  back  into  cliffs  of  notable  height,  and  the  bays  are 
as  a  iiile  too  deep  yet  to  have  been  filled  by  deltas  or  inclosed  by 
bars.  But  whei-o  the  coast  consists  of  ghicial  drift,  it  lias  already, 
in  the  present  cycle  of  shore  action,  been  nni<-h  altered,  the 
amount  of  modification  depending  chiefly  on  the  openness  of 
exposure  to  the  strong  waves  of  the  ocean.  Tiie  shore  along  the 
northern  side  of  Buzzard's  Bay  is  still  extremely  irregular,  its 
headlands  and  bays  hardly  being  changed  from  the  outline  they 
had  when  the  sea  first  lay  at  its  present  level.  Tlie  southern 
side  of  Cape  Cod,  somewhat  protected  by  the  outlying  islands, 
still  retains  something  of  its  original  irregular  outline,  although 
its  headlands  are  partly  cut  back,  and  its  liays  are  bridged  across, 
all  uniting  in  swinging  curves  of  greater  or  less  radius.  The 
southern  side  of  Martha's  Vineyard  is  much  simpler,  for  here 
stronger  waves  roll  along  the  shore,  and  the  coast  is  reduced 
almost  to  a  straight  line ;  half  the  headlands  being  already  con- 
sumed, and  only  half  the  liays  rtMiiaining.  The  outer  side  of 
Nantucket  seems  to  have  suffered  a  still  gi-eater  loss,  for  the 
headlands  that  once  separated  the  little  bays  of  its  coast  are  now 
cut  back  so  far  that  only  the  smallest  remnant  of  the  bay  heads 
can  be  detected.  The  eastern  side  of  Cape  Cod  is  for  the  greater 
part  a  long  straight  cliff  of  clay  and  sand,  surmounting  one  of 
the  finest  beaches  in  the  world.    Here  no  trace  of  the  original 


I'HE   COAST   LINE.  303 

iiTt'guliir  shore  line  remains.  When  the  coast  line  is  .studied 
carefully  on  the  plan  thus  suggested, — first  considering  the 
manner  in  which  the  original  coast  line  was  determined,  when 
the  land  and  sea  took  their  present  relative  position  ;  then  con- 
.sidering  theclianges  thus  t'ai'  2)rodu('ed  in  the  original  coa.st  line 
V)y  wave  and  cin'rcnt  action, — it  acquires  the  same  quality  of  en- 
livened interest  that  is  attached  to  the  study  of  the  development 
of  laud  forms :  it  becomes  a  subject  worthy  of  special  treatment. 
Geographical  Consequences  of  Coastal  Foum.  —  Some  of 
our  coasts  are  almost  uninhaltited,  becau.se  they  have  no  har- 
borage ;  for  example,  the  matured  cliff  coast  on  the  "  l)a(;k"  or  east 
side  of  Cape  Cod,  the  adolescent  .southern  coasts  of  Nantucket 
and  Martha's  Vineyard,  and  the  coast  of  Rhode  Island  west  of 
Point  Judith.  The  harbors  among  the  many  outer  islands  of 
the  half-drowned  coast  of  Mainc^  ha\e  developed  no  large  cities, 
Ijecause  the  islands  are  too  small  and  too  disconnected  to  favor 
the  concentration  of  population.  New  Ham]ishire,  ha\dng  tlie 
smallest  water  boundary  of  any  New  Englaiul  State,  is  the  only 
exception  to  the  rule  that  each  State  has  its  lai'gest  city  on 
a  harbor,  —  Portland,  Boston,  Providence,  New  Haven,  and  Bur- 
lington, all  attest  the  rule,  —  and  l)efore  inland  manufactures 
were  developed  New  Hampshire  itself  made  no  exception.  All 
these  harbor  cities  except  Bui-lington  have  grown  from  early 
colonial  settlements,  in  which  good  harborage  was  the  chief  ele- 
ment in  determining  location ;  but  the  causes  which  have  led  to 
the  greater  gi-owth  of  certain  harbor  settlements  than  of  others 
are  generally  to  be  found  in  some  complicated  relation  between 
coast  and  interior;  partly  also  in  political  influences,  such  as  ac- 
company the  location  of  a  State  cajjital ;  and  partly  in  seniority 
of  settlement.  Some  cities  on  drowned  rivers  have  the  advan- 
tage of  tide  water  a  number  of  miles  inland  from  the  general 
coast  line.     Bangor,  Augusta,  Norwich,  illustrate  this  relation. 

conclusion. 

It  is  only  after  a  clear  perception  of  the  forms  of  the  land  is 
gained  by  tracing  out  their  development  that  the  careful  teacher 
or  the  serious  student  is  prepared  to  undertake  the  discussion 
of  the  relation  of  geography  to  history.  In  no  way  so  well  as 
by  modern  physiographic  methods  are  the  facts  of  land  form 
bi'ought  clearly  before  the  mind.  Throughout  this  monograph  a 
knowledge  of  the  development  of  land  forms  is  not  urged  upon 


304  PHYSICAL   GEOGRAPHY    OF    SOl'THERX    NEW    ENGLAND. 

the  geographer  as  an  end  in  itself, — although  it  may  truly  be  re- 
garded as  a  worthy  end  of  s^tudy  by  those  who  wish  to  devote 
their  whole  time  to  it,  —  biit  as  the  best  means  to  another  end; 
namely,  the  ai)[)re('iation  of  the  facts  of  land  form  which  consti- 
tute the  foundation  of  all  thorough  geographical  study.  It  is 
often  maintained  that  a  devoted  study  of  the  facts  themselves, 
without  regard  to  their  moaning  or  development,  will  suffice  to 
place  them  clearly  enough  before  the  mind;  but  this  vieAv  is 
contradicted  both  by  general  experience  in  inaiiy  subjects  where 
rational  exiilaiiation  has  replaced  ein]iii-i('al  generalization,  and 
by  the  special  experience  of  geography  as  well.  Left  to  itself  as 
an  empirical  study,  in  which  the  development  of  land  foims  was 
hardly  allowed  to  enter,  it  has  languished  for  many  years,  until 
it  became  a  subject  for  continual  comi)laint.  Gradually  be- 
ginning with  easy  examples  like  sand  diuies  and  volcanoes  and 
deltas,  simple  explanations  of  form  as  a  result  of  process  were 
admitted.  To-day  it  is  only  by  those  who  fail  to  see  the  direc- 
tion of  geographical  progres.s,  and  who  are  ignorant  of  the  prog- 
ress already  gained,  that  objection  is  made  against  the  effort  to 
bring  every  gecigraphical  fact  under  the  explanatioii  of  natural 
processes.  No  one  of  active  mind  can  look  across  our  upland 
and  fail  to  gather  increased  pleasure  and  profit  from  understand- 
ing its  history.  No  one  who  looks  i;pon  geography  as  the  study 
of  the  earth  in  relation  to  man  can  contemplate  the  contrast  be- 
tween glaciated  New  England  and  non-glaciated  Carolina  with- 
out inqrdring  into  the  meaning  of  the  contrast :  he  might  as  well 
study  the  Sahara  and  tlie  Sudan  withoiit  asking  the  i-eason  for 
the  dryness  of  the  one  and  the  moisture  of  the  other.  It  is  a 
mistake  in  this  day  to  speak  of  the  many  islands  along  the  coast 
of  iMaine,  and  not  bear  in  mind  that  they  result  essentially  from 
the  lialf-drowning  of  the  margin  of  the  dissected  upland;  or  to 
mention  Narragausett  Bay  and  the  estuary  of  the  Tliames  with- 
out remembering  that  they  are  only  drowned  valleys,  one  wide, 
the  other  narrow;  or  to  contrast  the  rugged  coast  of  Buzzard's 
Bay  with  the  smooth  outer  side  of  Cape  Cod,  and  fail  to  see  that 
one  is  still  young  while  the  other  is  already  mature.  It  is  as 
much  in  the  spirit  of  jirotest  against  the  omission  of  pliysio- 
grapliic  explanations  in  the  common-school  teaching  of  our  home 
geography,  as  in  the  desire  to  bring  forward  the  salient  physio- 
graphic features  of  southern  New  England,  that  this  monogi'aph 
has  been  \vi'itten. 


THE    SOUTHERN    APPALACHIANS. 


By  C.  Willard  Hayes. 


THE   PKOVINCE   DEFINED. 

Draw  a  line  from  the  most  easterly  point  of  Kentuckj-,  south- 
eastward across  Virginia  and  North  (Jarolina,  to  Cape  Fear  on  the 
Atlantic.  This  will  form  the  bouudaiy  between  tlie  Northern 
and  Southern  Appalachians.  In  the  northern  division,  described 
by  Mr.  Willis  in  Monogi-aph  No.  6,  the  most  striking  character- 
istic is  the  large  number  of  parallel  linear  ridges  occiipying  the 
central  zone  between  the  Blue  Kidge  and  the  Alleghany  Front. 
Southward  from  the  line  above  indicated  the  linear  ridges  de- 
crease in  nuiuber  and  importance;  the  central  zone  becomes  a 
true  valley,  bounded  on  the  east  by  a  broad  complex  mountain 
belt  instead  of  a  single  range,  and  on  the  west  by  several  detachtHl 
plateaus.  Decided  differences  likewise*  appear  in  the  drainage  of 
the  two  divisions,  as  well  as  in  the  forms  of  relief.  On  the  nortli 
the  di'ainage  is  eastwai-<l  from  the  Alleghany  Front,  tlie  (ii-eat 
Appalachian  Valley,  and  the  Blue  Ridge,  bj''  streams  flowing 
directly  to  the  Atlantic,  or  westward  by  New  River  to  the  Ohio. 
The  line  between  the  two  divisions  indicated  above  is  approxi- 
mately on  the  divide  south  of  New  River,  beyond  which  no 
streams  break  through  the  Blue  Ridge  towiu-d  the  east,  iind  oiilj- 
one,  the  Tennessee,  escapes  from  the  valley  zone  toward  the 
west.  It  thus  appears  that  the  subdivision  of  the  Appalachi- 
ans into  a  northern  and  a  southern  division  is  not  arbitraiy, 
but  is  based  upon  broad  physiographic  diffei-ences  between  the 
two  regions.  These  differences  will  api^ear  more  prominently 
ill  the  course  of  the  detailed  description  of  the  Southern  Ai>i)a- 
lachians. 

(Copyright,  1895,  by  American  Book  Company.) 

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^08  THK    SOITHERN    APPALACHLiNS. 

The  Southern  Ai)palachiau  Pi-ovince  maj-  be  more  exactly 
defiued  as  the  rogiou  lyiug  southwest  of  a  liue  joiuiug  the  east- 
erumost  point  of  Kentucky  with  Cape  Fear,  and  hmited  on  the 
southeast,  south,  and  west  by  the  level  plains  which  border  the 
Atlantic,  the  Gulf,  and  the  Mississippi.  ^ 


PHYSIOGK.\PHIC'   DmSIONS    0¥   THE   SOUTHERN    APPALACHIANS. 

The  region  thus  defined  is  not  a  simple  physiographic  unit, 
but  is  highlj-  complex,  and  may  be  further  subdi\-ided  into  five 
well-marked  diWsions,  each  characteiized  by  the  prevalence  of  a 
•  listinct  type  of  surface.  The  boundaries  between  these  natural 
}>liysiographic  divisions  extend  lengthwise  of  the  province  (that 
is,  northeast  and  southwest),  and  they  are  therefore  long,  naiTow 
belts,  with  their  sides  approximately  imrallel.  Xamed  in  their 
order  across  the  province  from  southeast  to  northwest,  they  are 
(1)  the  Piedmont  Plain,  (2)  the  Apjialachian  Mountains,  (3)  the 
Appalachian  Valley,  (4)  the  Cumberland  Plateaus,  (5)  the  Interior 
Lowlands.  The  location,  boundaries,  and  chief  characteristics  of 
these  five  divisions  will  first  l)e  given,  followed  later  by  a  more 
detailed  account  of  the  three  which  more  strictly  constitute  the 
Southern  Appalachians. 

(1)  The  Piedmont  Plain  extends  along  the  southeastern  base 
of  the  Appalachian  Mountains.  Its  surface  has  a  gentle  east- 
ward slope  from  an  altitude  of  about  1,000  feet  at  the  western 
edge  to  250  or  300  feet  on  the  east,  where  the  crystalline  rocks 
of  which  it  is  chieiiy  composed  pass  beneath  the  sands  and  clays 
of  the  Coastal  Plain.  The  surface  is  not  that  of  a  smooth  j)lain, 
for  the  I'ivers  and  creeks  flowing  across  it  have  cut  deep  and 
rather  narrow  channels.  They  have  etched  and  roughened  a 
surface  once  much  smoother  than  now.  The  western  limit  of 
the  Piedmont  Plain  through  North  and  South  Carolina  and  a 
portion  of  Georgia  is  along  an  irregular  hue,  on  which  the  gentle 
slope  of  the  etched  plain  changes  to  the  steep  slopes  of  the  Blue 
Ridge  and  its  outliers,  the  eastern  members  of  the  Appalachian 
Mountain  System.  Farther  south  the  western  limit  is  not  so 
well  marked,  for  the  surface  of  the  mountain  belt  has  been  worn 
down  almost  as  smooth  as  the  plain  itself. 

(2)  The  Appalachian  Mountains  occu])y  a  narrow  belt  which 
extends  northeastward  from  eastern  Alabama,  and  swells  out  to 


PHYSIOGK.U^HIC  DIVISIONS.  309 

its  greatest  width  of  about  70  miles  in  western  North  Carolina. 
This  belt  is  not  dominated  liy  a  single  mountain  range,  but  is 
occupied  by  numerous  groups  of  mountains  of  nearly  equal  mag- 
nitude. To  the  eastern  members  of  this  complex  system,  disre- 
garding a  few  groiips  of  outliers  to  be  described  later,  the  name 
"  Blue  Ridge  "  is  generally  applied.  It  carries  the  main  divide 
I)etween  the  Atlantic  and  Gulf  drainage  southwest  ward  from  the 
Roanoke  in  Virginia,  across  North  Carolina,  to  the  Chattooga  and 
Tallulah  rivers  in  South  Carolina.  The  southeastern  slopes  of 
the  Blue  Ridge  are  exti'emely  steep,  forming  an  ii'regular  escarp- 
ment toward  the  Piedmont  Plain.  The  northwestern  slopes,  on 
the  other  hand,  are  usually  gentle,  with  slight  descent  to  the 
high  valleys  upon  that  side. 

The  northwestern  edge  of  the  mountain  belt  is  marked  by  a 
range  somewhat  higher,  but  less  continuous,  than  the  Blue  Ridge. 
This  is  called  the  Unaka  Range.  Toward  the  Virginia  line  it 
merges  into  the  Blue  Ridge,  and  thence  sonthwestward  diverges 
from  the  latter,  terminating  in  northern  Georgia.  Between  these 
two  bounding  ranges  is  a  long,  narrow,  triangular  area  charac- 
terized by  high  valleys,  above  which  rise  many  irregular  moun- 
tain masses,  most  of  their  summits  reaching  a  common  plane 
between  4,000  and  ."j,0()0  feet  above  sea  level.  The  culminating 
point  of  the  region  is  toward  its  northei'n  end  in  the  Black 
Mountains,  one  of  which,  Mitchell  Peak,  reaches  an  altitude 
of  6,711  feet. 

(3)  The  Great  Ai^palachian  Valley  consists  of  a  long,  narrow 
zone,  whose  surface  is  depressed  several  hundred  feet  below  the 
highlands  on  either  side.  It  is  not  a  simple  valley  belonging  to 
a  single  gi-eat  river  system,  but  is  a  structural  belt  within  which 
the  valley  type  of  surface  predominates.  Its  broad  curves  eon- 
form  to  the  structural  axes  of  the  Appalachians;  and  their  form, 
as  well  as  the  width  of  the  valley,  is  quiti^  iii<lependent  of  the  size 
of  the  stream  which  occupies  it.  Within  tliis  belt  are  many  ele- 
vations rising  from  800  to  1,800  feet  al)ove  its  general  level.  The 
highest  of  these  form  a  series  of  ridges  along  the  southeastern 
side,  of  which  Chilhowee  Mountain  may  be  regarded  as  the  type. 
In  other  parts  of  the  valley  are  long  even-ci-ested  ridges,  of  which 
Clinch  ]\Iountain  is  the  type,  rising  nearly  to  the  level  of  the 
highlands  on  either  side. 

(4)  The  Cumberland  Plateaus  occupy  the  next  belt  beyond 
the  Great  Valley,  their  eastern  escarpments  rising  abruptly  along 


310  THE   SOUTHEllN    APPALACHIANS. 

its  western  side.  They  occupy  a  belt  of  country  in  which  the 
plateau  type  predominates,  extendingwith  varyiugwidth,  through 
eastern  Kentucky  and  Tennessee  and  northern  Georgia  and  Ala- 
bama, nearly  to  the  Mississippi  line.  The  belt  reaches  its  great- 
est elevation  in  Kentucky,  and  has  a  gradual  descent  toward  the 
south  and  west,  finally  merging  into  the  Gulf  Coastal  Plain  in 
central  Alabama.  The  western  limit  of  the  belt  is  an  extremely 
irregular  escarpment,  well  marked  in  Alabama  and  Tennessee, 
but  becoming  indistinct  in  Kentucky. 

(5)  West  of  the  Cumlierland  Plateaus  is  a  broad  belt  of  coun- 
try forming  a  physiograx>liic  division  to  which  no  distinctive 
name  has  hitherto  been  applied.  It  extends  westward  to  the 
Tennessee  and  Ohio  rivers,  embracing  the  central  basin  and 
its  highland  lini  in  Tennessee,  and  the  blue-grass  region  and 
western  coal  field  of  Kentucky.  This  region  is  essentially  a 
plain  of  low  relief,  holding  the  same  relations  to  the  Cumber- 
land Plateaus  that  the  Piedmont  Plain  does  to  the  Appalachian 
Mountains.  It  is,  in  fact,  a  western  Piedmont  Plain.  In  order 
to  avoid  confusion,  the  region  is  here  called  the  Interior  Low- 
lands. 

From  the  foregoing  brief  outline  it  is  seen  that  the  Southern 
Appalachian  Province  is  composed  of  two  elevated  belts, — the 
Appalachian  Mountains  and  the  Cumberland  Plateaus, — sepa- 
rated by  a  depressed  zone,  the  Appalachian  Valley ;  while  on 
either  side  are  Piedmont  Plains, — the  Atlantic  Piedmont  on 
the  southeast,  and  the  Ohio  Piedmont  or  Interior  Lowlands 
on  the  northwest. 

THE   PROBLEM    AND   THE    KACTOKS. 

In  order  to  appreciate  the  significance  of  these  physiographic 
divisions,  and  to  understand  their  origin,  certain  fundamental 
physiographic  processes  must  be  thoroughly  understood.  Al- 
though they  have  been  explained  at  lengtli  in  an  earlier  mono- 
graph, those  that  are  particularly  applicable  to  this  region  will 
be  briefly  reviewed.  It  is  also  important  that  something  should 
be  known  of  the  geology  of  the  region — the  composition  of  the 
rocks  and  their  structural  relations — in  order  to  understand  the 
conditions  under  which  the  physiographic  forces  work :  hence  a 
veiy  brief  outline  of  the  geology  wiU  also  be  given  before  the 
several  divisions  are  described. 


PHYSIOGRAPHIC   FACTOKS.  311 

It  must  be  liorne  in  iniud  tliut  everywhere  on  the  earth's  siir- 
facM:'  where  there  is  kind  two  grund  pliysiographic  processes  ai'e 
going  on,  —  the  first  dlastrophism,  the  elevation  and  depression  of 
the  land  by  forces  acting  from  Ijeneatli ;  and  the  second  f/rada- 
tloH,  the  wearing-down  of  the  land  chictly  by  the  action  of  run- 
ning water.  Although  the  forces  producing  diastrophisin  have 
sometimes  elevated  and  at  other  times  depressed  the  surface  of 
the  Appalachian  Province,  the  elevations  have  been  greater  than 
the  depressions,  and  the  resultant  effect  has  been  a  gain  in  alti- 
tude. The  process  of  gradation  also  tends  in  some  places  to 
build  up  and  in  others  to  lowei-  the  surface  of  the  land ;  but  the 
lowering  liat<  been  far  more  common  than  the  building  ujj,  so- 
that,  on  the  whole,  the  effects  of  the  two  processes  have  been  in 
op])osite  directions.  Diastrophism  has  lifted  the  land,  and  grada- 
tion has  worn  down  its  surface.  At  times  the  former  proci'ss 
has  gained  upon  the  latter,  and  the  region  has  had  then  a  greater 
elevation ;  at  others  gradation  has  been  most  active,  and  the  sur- 
face has  been  worn  down  toward  sea  level.  Thus  the  present 
altitude  of  the  region  is  due  to  the  balance  between  the  two- 
gi-and  physiographic  processes,  while  the  forms  of  the  surface 
are  due  almost  entii'ely  to  the  character  of  the  matei-ials  on 
which  the  forces  of  gradation  are  at  work.  Dift'erences  in  the 
texture  and  structure  are  the  principal  causes  of  differences  in 
the  surface  forms,  and  so  of  the  physiographi(!  divisions  of  the 
Appalachian  Province  outlined  above.  Tiie  amount  of  elevation 
is  an  important  but  subordinate  cause  of  present  diffei-ences  of 
surface. 

A  brief  examination  of  the  way  in  which  the  process  of  grada- 
tion is  accomplished,  and  some  account  of  the  character  and 
structure  of  the  rocks  in  different  portions  of  the  Southern 
Appalachians,  will  make  clear  tlic  origin  of  its  physiographic 
subdivisions. 

Physiogkaphic  Factors.  —  The  manner  in  which  a  river  carves 
its  valley  has  already  been  explained  in  a  former  monograph, — 
that  on  "  Physiographic  Processes,"  by  IVIajor  Powell, — and  need 
be  only  bri(^tly  referred  to  here.  It  was  shown  that  when, 
through  the  action  of  diastrophie  forces,  a  river  finds  itself  flow- 
ing at  a  considerable  altitude  above  the  sea,  its  first  work  is  to 
wear  down  its  channel  to  near  sea  level  by  tlie  process  of  rrrtiral 
corrasion;  that  when  this  is  nearly  accomplished,  and  its  fall 
greatly  lessened,  it  swings  from  side  to  side  in  ever-widening 


:\V2  THE   SOUTHEllN   Arr.U.ACHUNS. 

<urvos,  and  broadens  its  valley  by  the  process  of  lateral  cona- 
siiiii :  and  that  the  two  are  accompanied  by  a  third  process,  that 
of  erosion,  by  which  the  general  surface  of  tlie  country  is  worn 
down,  its  steep  slopes  smoothed  out,  and  the  material  carried  to 
the  sea.  These  processes,  if  continued  snflficiently  long,  reduce 
the  surface  to  a  low,  level  plain, — a  hase-lcveled  phiin  if  the 
jirocess  is  nearly  complete,  and  a,  peneplain  if  some  ineqiaalities 
remain  unreduced.  Naturally  it  is  seldom  that  a  region  is  found 
in  which  the  pi-ocess  of  gradation  has  just  begun,  or  in  which  it 
lias  reached  completion  in  the  prodiiction  of  a  perfect  plain. 
Most  j)ortions  of  the  earth's  surface  show  the  process  in  a  more 
or  less  advanced  stage.  This  is  true  of  the  Southern  Appala- 
<*hian  region,  and  the  fonns  of  its  surface  ai'e  such  as  character- 
ize various  stages  of  the  process.  At  each  stage  three  factors 
are  important  in  determining  the  details  of  the  land  surface  in 
any  region.  These  are  (1)  the  chai'acter  of  the  i-ocks  considered 
with  reference  to  their  ability  to  resist  erosion;  {'!)  the  alterna- 
tion of  hard  and  soft  beds;  and  (3)  the  altitude  of  the  beds  with 
reference  to  a  horizontal  plane. 

It  is  evident  that  soft  rocks — i.e.,  those  that  are  sohilile  (as 
limestone),  or  which  crumljle  readily  when  exposed  to  the  air  (as 
calcareous  shales) — will  be  worn  down  and  carried  away  more 
rapidly  than  those  which  are  composed  of  insoluble  material,  and 
are  not  affected  by  weathering  (as  quartzite  and  argillaceous 
slate).  Hence,  where  the  initial  altitude  is  the  same,  areas 
undei'lain  by  tlic  first  class  of  rocks  will  l)e  soonest  reduced  to 
base-level,  and  may  form  low  level  plains ;  while  the  areas  under- 
lain by  hard  rocks,  although  subjected  to  the  same  agencies  of 
degradation  for  the  same  hmgth  of  time,  remain  above  base-level 
as  mountains  or  hills.  Again,  if  beds  of  different  character  alter- 
nate, as  beds  of  limestone  with  beds  of  quai'tzite,  the  latter  are 
more  readily  broken  down  by  imdermining  and  sapping  than 
where  the  whole  mass  is  composed  of  homogeneous,  even  though 
less  resistant,  material.  Finally,  if  the  beds  are  horizontal,  they 
give  a  totally  dift'ereut  form  to  the  smface  (hiring  gradation  tlian 
if  they  are  steeply  inclined,  especially  if  there  is  at  the  same 
time  an  alternation  of  hard  and  soft  beds.  Tn  this  case  the 
streams  first  ciit  narrow  gorges  bounded  by  cliffs  which  recede 
as  already  explained,  the  hard  beds  forming  the  escarpments  of 
terraces,  and  the  intervening  soft  beds  forming  their  level  tops 
or  gentle  slopes.     If,  on  the  other  hand,  the  strata  are  steeply 


(iEol-Odlf    FACTOKS.  313 

inclined,  any  i)articulai'  hard  bed  quickly  passes  below  the  base- 
level  of  erosion.  'J'lie  soft  beds  are  rapidly  worn  down  to 
this  level,  while  ihc  liard  bed  [jvojects  as  a  narrow  lidge  or  line 
of  knobs. 

While  the  altitude  of  the  region,  as  stated  above,  is  the  re- 
sidtant  of  the  two  processes  elevation  and  gradation,  the  manner 
in  which  the  elevation  took  ])hice  has  exercised  a  controlling 
influence  over  the  t()i)ograi)hic  forms.  In  outlining  the  physio- 
graphic divisions,  it  was  stated  that  no  dominant  range  over- 
topped its  iieighl)oi-s  in  either  of  the  highland  belts.  On  tiie 
contrary,  in  the  Api)alachian  ^Mountains,  where  such  a  dominant 
range  might  be  looked  foi-,  the  greater  number  of  summits  reach 
nearly  to  a  common  plane.  If  the  present  altitude  of  the  region 
had  been  attained  during  a  single  period  of  elevation,  either 
gradual  or  rapid,  there  would  Ije  nmch  greater  diversity  in  the 
height  of  different  portions.  The  altitude  of  any  part  of  the 
surface  would  then  represent  almost  exactly  the  pr(»duct  of  two 
factors,  —  (1)  the  resistance  of  the  material  at  that  particular 
l)oint,  and  ('J)  the  nearness  to  main  drainage  lines.  High  points 
might  be  du(^  to  relatively  soft  rocks,  if  favorably  situated  far 
from  master  streams,  or  to  hard  I'ocks  not  so  situated ;  while  the 
highest  points  would  result  from  a  combiiuition  of  luirdest  rocks 
and  most  favorable  location.  The  absence  of  dominant  peaks, 
then,  taken  in  connection  with  other  facts,  indicates  that  the 
♦'Icvation  has  not  been  accomplished  in  a  single  period,  Imt  has 
consisted  of  a  series  of  comparatively  rajjid  movements,  sepa- 
rated by  long  pei-iods  of  r(>st.  During  th<'  latter  the  forces  of 
gradation  repeatedly  wore  down  the  surface  to  a  more  or  less 
perfect  plain.  The  soft  rocks  were  protected  below  the  base- 
level  of  erosion  until  anoth(>r  ui)lift,  while  the  hard  rocks  were 
7'educed  nearly,  if  not  ciuitc,  to  that  level:  hence  difference  of 
rock  texture  was  not  permitt(Ml  to  exercise  its  full  influence  on 
the  relief,  but  was  kept  within  certain  definite  limits  by  the  for- 
mation of  siU'cessive  peneplains. 

(tEGLOGIC  Factous.  —  The  southeastern  portion  of  the  Appa- 
lachian Province  —  i.e.,  tli(>  Piedmont  Plain  and  a  part  of  the 
mountain  belt  —  has  probalily  l)eenalaud  area  since  the  earliest 
geologic  periods  of  which  we  have  record.  The  rocks  are  almost 
wholly  crystalline,  in  part  sediments  which  have  been  rendered 
<'rystalline  by  heat  and  pressure,  and  in  part  rocks  which  have 
<'ooled  and  crystallized  from  a  molten  condition.     The  former 


314  THE  SOUTHERN   APPALACHIANS. 

are  called  metanwrphic,  aud  the  latter  eruptive  rocks;  but  they 
sometimes  resemble  each  other  so  closely  that  it  is  uot  always 
possible  to  distinguish  them. 

During  all  or  the  greater  part  of  Paleozoic  time  the  region  to 
the  northwest  of  the  Appalachian  Mountains  was  occupied  by  a 
sea  in  whidi  sediments  deiived  from  the  old  land  to  the  south- 
east were  being  deposited.  When  er(.)si(.)n  of  the  land  was  rapid, 
by  reason  of  its  gi-eat  altitude,  the  streams  carried  down  coarse 
material,  sand  and  gravel,  which  was  spiead  over  the  sea  bottom 
mostly  near  tlie  shore,  and  now  forms  beds  of  sandstone  and 
conglomerate.  "\\Tien  the  old  land  had  Ijeen  partly  worn  down, 
the  streams  carried  only  fine  sand  and  mud,  which  was  more 
widely  distributed  ])y  waves  aud  currents,  and  now  appears  as 
shale.  Finally,  when  the  surface  was  so  far  reduced  that  the 
streams  became  sluggish,  they  could  carr}-  only  materials  in 
solution,  chiefly  car])onates  of  lime  and  magnesia,  which  were 
deposited  on  tlie  sea  floor  partly  through  the  agency  of  animals, 
and  jiartly  as  a  chemical  precipitate.  Thus  were  formed  the 
great  beds  of  limestone  and  dolomite.  All  the  beds  thus  laid 
do'svn  were  originally  nearly  horizontal,  though  uot  entirely  so ; 
for  some  parts  of  the  sea  bottom  appear  to  have  been  depressed 
more  than  others,  as  though  by  the  weight  of  sediment  heapeil 
upon  them. 

Finally,  near  the  close  of  Paleozoic  time,  the  interior  sea  di- 
minished in  size  by  the  emergence  of  nuich  of  its  bottom  to  form 
dry  land.  At  the  same  time,  tbe  crust  of  the  earth  contracted, 
so  that  great  wrinkles  i-ose  upon  its  surface  as  they  do  upon  a 
withered  apple.  These  wrinkles  were  not  uniformly  distributed, 
but  were  confined  to  narrow  belts  along  certain  lines,  which  ap- 
pear to  have  been  lines  of  weakness,  where  the  strata  couhl  be 
most  easily  bent  and  broken.  In  this  manner  the  strata  within 
a  zone  from  75  to  150  miles  in  width,  stretching  from  New  York 
to  central  Alabanui  and  an  unknown  distiince  beyond,  have 
been  thrown  into  a  series  of  long,  luirrow,  i)arallel  folds.  On 
the  southeast  is  the  original  land  area  from  which  the  interior 
sediments  were  derived,  its  crystalline  rocks  forming  a  massive 
buttress  against  which  the  sediments  were  tlirust  and  bent.  To 
the  northwest  of  the  folded  belt  the  strata  stretch  for  many 
miles  across  the  Mississippi  Valley,  with  but  little  change  from 
their  original  horizontal  position.  Tlie  subdivisions  of  the  Ap- 
palachian Province  were  thus  determined  long  before  the  incep- 


THE   CUMBERLAND   PLATEAUS.  315 

tion  of  the  sculpturing  processes  which  have  giveu  to  them  their 
distinctive  forms. 

The  mountain  l)elt  is  the  seaward  portion  of  tlie  old  Paleozoic" 
continent  from  which  the  rocks  to  the  westward  were  derived; 
the  Great  Valley  is  the  landward  portion  of  the  Paleozoic  sea  in 
which  the  coarse  sediments  were  mostly  deposited,  and  to  which 
the  subsequent  folding  was  mostly  confined ;  while  the  plateaus 
are  composed  of  the  offshore  deposits,  Avhich  retain  their  original 
horizontal  position. 


DESCRIPTION   OF   THE   PHYSIOGRAPHIC   DIVISIONS. 

Bearing  in  mind  the  princii)l('s  of  physiography  outlined 
above,  and  the  differences  in  geologic  structure,  we  are  now  pre- 
pared to  examine  more  in  detail  the  forms  of  relief  of  the  vari- 
ous subdivisions  of  the  Southern  Appalachians,  and  to  trace  the 
cotmection  between  structure  and  topographi(!  form.  Only  the 
two  belts  of  highland,  with  the  intervening  valley,  will  be  con- 
sidered ;  the  Piedmont  Plain  and  the  Interior  Lowlands  lying 
beyond  the  scope  of  this  paper. 

The  Cumberland  Plateaus. — The  western  of  these  three 
divisions,  the  Cumberland  Plateau,  will  be  taken  up  first,  since 
it  presents  the  simplest  pliysiographie  eontlitious.  The  rocks 
which  form  the  surface  in  this  region  are  of  Carboniferous  age, 
and  consist  of  sandstones,  shales,  and  limestones.  The  lime- 
stones lie  beneath  the  sandstones,  while  the  beds  of  shale  alter- 
nate with  beds  of  sandstone,  and  all  tlu^  strata  are  nearly  hori- 
zontal. The  limestone  is  degraded  eliiefly  by  solution  ;  while  the 
sandstone  is  insoluble,  and  can  be  worn  chnvn  most  readily  by 
undermining  and  sapping.  As  soon,  therefore,  as  the  streams 
by  vertical  corrasion  have  cut  through  the  sandstones  and  shales 
into  the  underlying  limestone,  they  are  bounded  by  cliffs,  and 
the  degradation  of  the  entire  region  is  effected  chiefly  by  their 
recession.  The  slopes  are  kept  steep  by  the  more  rapid  removal 
of  the  lower  limestone  than  of  the  upper  sandstone  beds.  The 
beds  of  sandstone  form  steep,  often  vertical  edges  of  terraces, 
while  the  intervening  beds  of  shale  form  their  more  or  less  gently 
sloping  surfaces.  It  is  chiefly  in  the  central  portion  that  the 
plateau  character  is  well  marked.  In  northern  Georgia  and  Ala- 
bama and  the  adjacent  portions  of  Tennessee  the  conditions  are 


31G  *         THE    SOUTHERN    A1'1'AI.\(  111 AXS. 

favorable  for  the  ilevelopnieut  ami  in-isisit'iice  of  steep  esrai-p- 
jiu'Uts  bouiidiiijr  level  plateaus.  Fartlier  south  the  base  of  tlie 
samlstoue  is  so  low  that  the  streams  d<>  not  reaeh  the  limestone, 
and  hence  the  process  of  sapping,  l)y  whicli  the  cliffs  recede  while 
retaining  their  steep  slopes,  is  not  favored.  The  same  is  true  in 
eastern  Kentucky  and  the  adjacent  i)ortions  of  Tennessee.  Also 
in  the  latter  regions  the  sandstones  are  nearly  honutgeneous,  and 
do  not  afford  the  strong  contrasts  between  altciiuiting  licds 
Avhich  are  favorable  for  the  formation  of  cliffs:  lu'iice  the  slopes, 
althoiigh  steep,  are  smooth  from  top  to  bottom,  and  the  region 
is  cut  into  hills  with  siiarii  or  rounded  summits. 

The  opposite  sides  of  the  plateau  are  formetl  by  abi-ui>t  escarp- 
ments. That  on  the  east,  fronting  upon  the  Appalachian  X'allcy, 
is  generally  straight  or  broadly  curved,  except  for  a  single  abrujit 
bend  which  it  makes  north  of  the  Emory  Ki  ver.  Here  the  escarp- 
nuMit  turns  from  its  northeast  course  sharply  toward  the  north- 
west for  a  few  miles,  and  then  resumes  its  former  direction.  The 
western  escarpment,  on  the  other  hand,  is  extremely  irregular. 
Streams  flowing  westward  from  the  plateau  have  cut  deep  reen- 
trant angles  far  within  its  edge,  leaving  many  narrow  spurs  pro- 
jecting into  the  lowland  beyond.  This  difference  between  the 
escarpment  on  opposite  sides  of  the  plateau  is  due  chiefly  to  the 
attitude  of  the  underlying  rocks.  Toward  the  Avest  the  strata 
extend  for  a  long  distance  nearly  horizontal.  The  highland  has 
been  converted  into  lowland  by  erosion  of  the  face  of  the  escarp- 
ment liy  the  process  of  cliff"  recession  already  described  ;  and  this 
recession  has  been  irregular, — most  rapid  where  the  streams 
could  l)ear  away  the  debris  from  the  base  of  the  cliff's,  and  least 
ra])id  far  from  the  larger  streams,  where  the  transporting  power 
of  the  water  was  small :  hence  the  deeply  rei'utrant  coves  and  the 
strongly  salient  spurs.  The  form  of  the  eastern  escarpment,  on 
the  other  hand,  does  not  depend  on  the  accidents  of  cliff  reces- 
sion, for  the  recession  is  controlled  by  the  attitude  of  the  strata. 
As  already  indicated,  the  region  east  of  the  ])latean  is  cliarac- 
tenzed  by  steeply  inclined  strata.  The  folding  which  they 
have  sutt'ert^d  has  brought  underlying  soft  limestones  and  shales 
high  above  the  base-level  of  erosion,  where  they  were  attacked 
and  worn  away.  At  the  present  escarpment  the  strata  dip 
steeply  to  the  westward,  carrying  the  soft  I'ocks  below  the 
base-level,  and  presenting  a  barrier  of  hard  rocks  beyond 
which  erosi,ou  has  not  yet  been  able  to  go:   in  other  words, 


TH1-:    Ari'ALAtlllAN    VALLEY.  'All 

the  position  of  the  escarpmeut  depends  on  the  position  of  the 
westernmost  of  tlie  steejj  folds  ehavacteriziug  the  Appalachian 
\'alley  belt. 

From  the  Emory  River  southward  to  the  Tennessee  at  Chat- 
tanooga, the  eastern  boundary  of  the  plateau  is  a  linear  escarp- 
ment ;  but  twelve  miles  to  the  west  is  a  narrow  valley,  jierfectly 
straight,  and  also  bounded  by  parallel  linear  escarpments.  Tiiis 
is  Sequatchie  Valley.  Its  position  and  form  are  directly  depend- 
ent upon  a  narrow  anticlinal  fold,  which  extends  i)arallel  with 
t  lie  folds  in  the  belt  to  the  eastward,  and  which  lifted  the  plateau 
sandstone  so  far  above  base-level  that  it  was  easily  removed,  ex- 
posing the  underlying  soft  limestone  to  erosion.  The  process  Ijy 
which  this  linear  valley  was  formed  is  still  going  on  at  the  north- 
ern enil  of  the  anticline,  whei-e  the  ai'chiiig  strata  are  not  yet 
wholly  removed.  They  form  the  Crab  Orchard  Mountains,  which 
extend  northward  directly  in  line  with  the  Sequatchie  Valley. 
Wherever  the  protecting  cai:>  of  sandstone  has  been  rejnoved, 
deep  coves  are  formed  in  the  underlying  limestone.  These  are 
often  surrounded  by  a  lim  of  sandstone,  and  the  water  collecting 
in  them  flows  off  through  subterranean  ]tassages  which  it  has 
formed  by  the  solution  of  tlie  limestone. 

From  the  southern  border  of  Tennessee,  southward  well  into 
AlaV)ama,  the  plateau  is  separated  into  three  or  more  nari'ow 
strips  by  parallel  anticlinal  valleys,  one  of  them  tlie  continuation 
of  Sequatchie  Valley,  an<l  tlu*  others  formed  in  exactly  the  same 
manner.  The  easternmost  of  these  narrow  plateaus  is  Lookout 
j\[ountain,  which  terminates  in  a  high  alirupt  jtoint  at  Chatta- 
nooga. Southward  from  this  2)oint  the  mountain  widens  slightly, 
and  towtird  the  southern  end  changes  its  form  from  a  level- 
topped  i)lateau  to  a  shallow  trough,  the  pai-allel  escai'pments 
passing  into  monoclinal  ridges,  which  terminate  abriiptly  in 
Alabama  at  Gadsden  and  Attalla.  West  of  Lookout  Mountain, 
and  separated  from  it  by  Lookout  and  Wills  valleys,  is  Sand 
Mountain,  the  soxithward  continuation  of  Walden  Plateau,  and, 
like  it,  bounded  by  parallel  linc^ir  escai'pments.  Bej'^ond  Sand 
Mountain  is  the  Cumberland  Plateau  proper,  in  northern  Ala- 
bama, so  deeply  dissected  that  only  isolat(Ml  mesas  remain,  but 
south  of  the  Tennessee  River  forming  a  bi-oad  table-land  sloping 
gently  southward. 

The  Appalachlvn  Valley.  —  As  already  stated,  the  Great  Aji- 
palachian  Valley  is  located  u]ion  a  licit  of  intensely  folded  strata, 


318  THE   SUITHEKX    APPALACHUNS. 

and  to  the  structure  and  character  of  the  rocks  it  directly  owes 
its  characteristic  features.  Its  several  portions  are  occupied  by 
ilistiuct  river  systems,  and  the  position  and  form  of  the  valley 
are  independent  of  the  position  and  size  of  the  streams  it  bears. 
The  valley  has  a  width  of  about  45  miles  in  northern  Georgia  and 
Alabama,  50  miles  opposite  the  broadest  portion  of  the  Appala- 
chian Mountains,  expanding  to  65  miles  in  northern  Tennessee, 
and  contracting  to  30  miles  in  southern  Virginia.  The  western 
side  of  the  valley  is  formed  by  the  plateau  escarpment  rising 
abruptly  from  800  to  1,500  feet,  its  summit  everywhere  present- 
ing an  almost  perfectly  straight  horizon.  East  of  the  Great  Val- 
ley rise  the  Unakas,  their  .sharp  or  rounded  summits  forming  a 
sky  line  totally  different  from  that  to  the  west. 

To  one  traversing  this  region  l)y  rail  its  true  character  is  not 
apparent.  He  sees  innumerable  hills  and  ridges  of  varying 
lieights  inclosing  broad  or  narrow  valleys,  according  to  the  size 
of  the  stream.  The  limiting  highlands  are  generally  hidden  by 
the  nearer  elevations,  and  it  is  seldom  that  both  can  be  seen  at 
the  same  time.  If,  however,  the  observer  ascends  to  the  high- 
land on  either  side,  the  hills  and  ridges  which  give  character  to 
the  country  as  seen  from  below  appear  only  as  minor  inequalities 
of  the  surface.  Tlie  region  is  essentially  a  broad  plain  within 
whose  surfaces  the  streams  have  carved  their  valleys  from  50  to 
:500  feet. 

The  ridges  which  occur  in  various  portions  of  the  valley  belt 
may  be  classified  in  three  groups.  In  the  first  are  those  which 
approach  in  altitude  the  plateau  escarpments  and  the  high  val- 
leys of  the  Appalachian  Mountains.  To  this  class  belong  Clinch, 
Bays,  and  White  Oak  mountains,  in  Tennessee;  and  Taylor.s, 
Chattooga,  Gaylor,  Dirtseller,  and  Cohin  mountains,  in  Georgia 
and  Alabama.  These  are  all  narrow  ridges,  some  of  them  of 
great  length,  extending  parallel  with  the  sides  of  the  valley  belt. 
Their  crests  are  almost  perfectly  horizontal,  making  an  even  sky 
line  like  the  plateau  escarpment.  These  ridges  are  formed  by  a 
liard  bed  of  Silmian  sandstone  of  uniform  thickness,  which  usu- 
ally dips  steeply  to  the  east.  Soft  beds  above  and  below  have 
been  worn  down,  lea^-ing  the  hard  one  projecting  as  a  ridge. 
The  reason  for  this  uniform  altitude  and  these  even  crests  will 
be  given  later. 

The  t^-pe  of  the  second  class  of  valley  ridges  is  the  Chilhowee 
Range,  which  lies  along  the  western  base  of  the  more  massive 


THE   BLUE  RIDGE.  319 

Unakas.  It  includes  Holston,  Irou,  Euglish,  Chilhowee,  Starrs, 
and  Beans  mountains,  in  Tennessee ;  and  Indian,  Weisner,  Cho<'- 
colocro,  and  Terrapin  mountains,  in  Alabama.  These  differ  from 
the  Chnch  Mountain  tyj)o  in  their  greater  altitude  and  less 
regular  crests.  They  are  due  to  massive  beds  of  Cambiian 
quartzite,  which  is  more  resistant  than  the  Silurian  sandstone, 
and  hence  produces  higher  ridges;  but,  on  tlie  other  hand,  it 
is  less  uniform  in  thickness,  so  that  the  resulting  ridges  have 
less  even  crests. 

The  third  class  includes  the  very  large  number  of  low  eleva- 
tions that  make  up  the  minor  irregularities  of  the  surface, — broad 
rounded  hills,  sharp  knobs,  and  narrow  ridges,  rising  from  100 
to  :!00  feet  aljove  the  streams.  Their  foi-m  is  dependent  cliiefly 
on  the  character  of  the  material,  the  degree  of  relief,  or  the  near- 
ness to  the  main  di'ainage  lines.  Seen  from  an  elevation  at  the 
edge  of  the  valley,  these  minor  irregularities  appear  as  a  series 
of  green  billows,  all  reaching  nearly  the  same  level,  above  which 
rise,  like  islands,  ridges  of  the  Clinch  and  Chilhowee  tyi^es:  in 
other  words,  the  elevations  of  this  class  reach  a  common  plane, 
above  which  rise  the  larger  lidges  and  highlands,  and  below 
wliich  the  present  valleys  of  the  streams  nn.',  sunk.  The  signifi- 
cance of  this  plane  will  be  pointed  out  later. 

The  Appalachian  Mountains. — Having  briefly  described  the 
topography  of  the  adjoining  physiogi'aphic  districts,  the  main 
Appalachian  Mountain  belt  will  be  next  taken  up.  Some  of  its 
more  prominent  features  have  already  been  outlined,  and  will 
now  be  considered  in  greater  detail. 

The  belt  is  not  a  unit  dominated  by  a  single  range  or  gi'oup 
of  mountains,  but  is  complex,  containing  several  elements  of 
nearly  equal  importance.  These  are  (1)  the  Blue  Ridge,  ("2)  the 
Eastern  Monadnocks  and  Piedmont  Valleys,  (3)  the  Unaka  Kange, 
(4)  the  Central  Mountain  Groups  and  Intermontane  Valleys. 

The  Blue  Ridfie. — The  Blue  Ridge,  carrying  the  nniin  divide 
between  the  Atlantic  and  (luif  drainage,  is  everywhere  nearer  the 
eastern  than  the  western  side  of  the  mountain  belt;  and,  neglect- 
ing a  few  groups  of  outlying  mountains  whose  mass  is  insignifi- 
cant compared  with  those  west  of  the  divide,  the  Blue  Ridge  may 
be  regarded  as  fornung  the  extreme  eastern  range  of  the  Api)ala- 
chian  Mountains.  It  reaches  its  greatest  height  in  (xrandfather 
Mountain,  with  an  altitude  of  5,964  feet.  Thre(>  other  points 
reach  above  5,000  feet;  and  a  dozen  or  mor(\  most  of  them  in 


3'JO  THK    SOVIHEUN    APP.VL.UHIAXS. 

North  Carolina,  above  4,U00  feet.  The  gaps  show  a  somewhat 
regular  decrease  iu  altitude  on  either  side  of  the  cuhiiiuating 
point,  from  4,000  feet  iu  the  vicinity  of  Grandfather  Mountain, 
to  '2,'200  feet  near  the  South  Carohna  line,  and  2,700  at  the  Vir- 
ginia line. 

The  most  striking  characteristic  of  the  Blue  Ridge  is  the  gi-eat 
difference  in  slope  on  its  opposite  sides.  The  streams  heading 
in  the  gaps  upon  the  di\'ide  flow  westward  in  broad,  smoothly 
rounded,  and  drift-filled  valleys  for  many  miles  before  entering 
the  naiTOw  rock-cut  gorges  of  their  lower  coiu'ses.  Tliose  flow- 
ing eastward,  on  the  other  hand,  plunge  immediately  do^^^lward 
iu  a  series  of  cascades,  falling  several  thousand  feet  in  a  few 
miles.  They  have  no  valleys,  only  V-shaped  gorges  until  they 
reach  nearly  to  the  level  of  the  Piedmont  Plain.  This  difference 
in  slope  is  adniiiably  shown  on  the  Southern  Railway  from  Ashe- 
ville  to  Salisljury,  N.C.  From  Asheville  eastward,  the  road  as- 
cends the  valley  of  the  Swanuanoa  with  an  easy  grade,  making 
directly  for  the  gap.  Passing  the  di\dde,  it  descends  upon  the 
head  waters  of  the  Catawba  by  an  intricate  series  of  loops,  wind- 
ing back  and  forth  upon  the  mountain  side  in  such  a  way  that 
at  one  point  three  tracks  can  be  seen  one  above  another,  and  a 
descent  of  1,100  feet  is  accomplished  between  points  only  ;> 
miles  apart  in  an  air  line.  Reaching  the  level  of  the  Catawba 
at  an  altitude  of  1,400  feet,  the  road  again  follows  a  broad  valley 
with  easy  gi-ade  down  to  the  Piedmont  Plain,  which  it  reaches  50 
miles  to  the  eastward,  at  an  elevation  of  1,000  feet.  Northward 
from  the  Virginia-North  Carolina  line  —  that  is,  in  the  Northern 
Appalachians  —  the  Blue  Ridge  presents  a  comparatively  smooth 
and  regular  face  toward  the  east ;  and  as  far  as  the  Roanoke  River 
the  divide  is  upon  the  extromo  eastern  edge  of  the  mountain  belt. 
Southward  in  North  Carolina  the  divide  is  usually  some  distance 
from  the  edge  of  the  belt,  and  many  long  spurs  extend  from  the 
main  ridge  toward  the  south  and  soiitheast.  They  are  separated 
by  deep  vaUeys,  which  often  broaden  into  coves  shut  in  by  steep 
mountain  walls.  The  most  extensive  of  these  spurs  are  at  the 
head  waters  of  the  Yadkin  and  Catawba  rivers,  in  the  central 
])ai-t  of  western  North  Carolina.  The  eastward-flowing  streams 
liave  cut  back  into  the  mountain  belt,  and,  haA-ing  the  advan- 
tage of  a  more  direct  course  to  the  sea,  have  encroached  upon 
the  territory  of  westward-flowing  streams,  —  the  New,  Watauga, 
Noliehucky,  and  French  Broad  rivers,  —  and  have  robbed  them 


MONADNOCKS   AND   PIEDMONT   VALLEYS.  321 

of  portions  of  their  drainage  basins.  Thus  the  Lin\dlle  River, 
a  northern  tributary  of  the  Catawba,  has  cut  through  the  Blue 
Ridge  proper,  so  that  the  hitter  forms  a  spur  extending  south- 
ward from  Grandfather  Mountain  for  20  miles,  the  divide  being 
on  a  less  elevated  ridge,  parallel  ^vith  it,  and  a  few  mUes  to  the 
west. 

The  Blue  Ridge,  bearing  the  main  divide,  has  a  direct  south- 
westerly course,  with  only  minor  deviations,  across  North  Caro- 
lina. At  the  South  Carolina  line  the  divide  turns  abruptly  to 
the  northwest,  making  two  Iwoad  loops  which  inclose  the  basins 
of  the  Chattooga  and  Tallulah  rivers.  South  of  the  latter  the 
divide  returns  to  its  former  southwesterly  course  along  the 
southeastern  side  of  the  Chattulioochce  River.  The  Blue  Ridge 
itself,  though  not  followed  by  the  main  divide,  continues  south- 
westward  across  the  corner  of  South  Carolina  as  the  Chattooga 
Ridge,  and  beyond  the  Chattooga  River  into  Georgia  as  the 
( 'hattahoocliee  Ridge.  Th(»  latter,  at  no  point  more  than  1,600 
feet  in  altitude,  gradually  merges  into  the  Piedmont  Plain 
before  reaching  Atlanta. 

The  Eastern  Mntiadnocks  and  Piedmont  Vallei/s. — In  addition 
to  the  spurs  from  the  Blue  Ridge  mentioned  above,  there  are 
several  groups  of  mountains  along  the  extreme  eastern  border  of 
the  mountain  belt,  which  have  been  more  or  less  completely 
isolated  by  the  erosion  of  eastward-flowing  streams.  The  most 
important  are  the  Brushy,  South,  and  Saluda  mountains.  The 
iirst-named  group  lies  between  the  Yadkin  and  Catawba  rivers, 
extending  for  50  miles  nearly  parallel  with  the  Blue  Ridge,  and 
l)etweeu  15  and  25  miles  distant  from  the  main  divide.  The 
liighest  points  reach  an  altitude  of  2,700  feet,  while  the  gap 
between  this  gi-oup  and  the  Blue  Ridge  is  only  1,300. 

South  of  the  Catawba  River  are  the  South  Mountains,  which 
extend  for  50  miles  nearly  east  and  west,  their  axis  making  a 
large  angle  with  the  Blue  Ridge  divide.  A  few  points  reacli  an 
altitude  of  3,000  feet,  or  about  1,800  feet  above  the  level  of  the 
(Catawba  and  Broad  rivei-  valleys. 

Tlie  third  gi'oup,  the  Saluda  Mountains,  also  trend  nearly 
east  and  west,  their  crest  forming  the  boundary  between  North 
and  Soutli  Carolina  for  about  20  miles.  They  are  liiglier  than 
the  others  described,  reaching  3,100  feet,  but  are  much  less  com- 
])letely  isolated,  and  may  be  considered  as  a  spur  from  the  Blue 
Ridge. 


322  THE   SOUTHEKN    APPALACHIANS. 

These  three  mouutain  groups  are  isolated  from  the  Blue  Ridge 
and  from  one  another  by  the  Yadkin,  Catawba,  and  Broad  river 
valleys.  The  latter  are  simply  portions  of  the  Piedmont  Plain, 
with  which  they  are  continuous  toward  the  east.  They  may  be 
regarded  as  bays  projecting  westward  from  that  plain  between 
headlands  formed  by  the  mountain  groui)s. 

All  of  these  groups  are  deeply  dissected  by  ei'osion.  Although 
once  massive  continuous  ranges,  they  are  now  cut  by  deep 
ti'ansverse  valleys  into  manj"  short  ridges  and  peaks.  Their 
altitude  decreases  toward  the  east,  and  thej^  give  place  in  that 
direction  to  isolated  knobs  entirely  surrounded  by  the  Piedmont 
Plain. 

It  is  evident  that  these  outlying  groups  form  an  integral  part 
of  the  Appalachian  Mountain  system.  The  main  divide  was 
formerly  far  to  the  east  of  its  pi'esent  position,  but  it  is  slowly 
migrating  westward.  The  Atlantic  di'ainage  has  the  great  advan- 
tage of  a  much  shorter  course  to  the  sea,  and  hence  steadily  en- 
croaches upon  the  territory  of  streams  flowing  westward.  TJjc 
Catawba,  Yadkin,  and  Broad  rivers  have  pushed  the  divide  west- 
ward, and  reduced  the  immediately  adjacent  conquered  territory- 
to  the  level  of  the  Piedmont  Plain,  which  v;ntil  very  recently 
was  the  base-level  of  erosion.  The  regions  between  these  streams 
they  have  not  yet  had  sufficient  time  to  reduce  completely,  so 
that  groups  of  mountains  there  remain  which  are  the  I'esiduals 
of  a  former  continuous  highland:  in  other  words,  they  are 
Monadnocks  more  or  less  typically  developed. 

In  cases  of  recent  capture,  the  stream  valleys  remain  nearly 
at  the  elevation  of  the  l)eheaded  stream.  Thus  the  upper  por- 
tion of  the  Linville  Valley  has  an  altitude  above  3,800  feet;  and 
the  stream,  after  flowing  for  10  miles  in  a  broad  open  valley, 
plunges  into  a  narrow  gorge  with  a  fall  of  1,000  feet  in  less  than 
3  miles.  The  upper  valley  of  the  Catawba,  on  the  other  hand, 
is  below  1,500  feet,  and  oidy  the  smallest  tril)utaries  have  rapid 
fall.  In  the  lattei'  case  the  conquered  territoiy'  is  thoroughly 
subjected;  in  the  former  the  capture  has  been  recent,  and  the 
reduction  is  not  complete. 

The  Uriaka  lianqr.  —  The  Unaka  Range  forms  the  northwest- 
ern member  of  the  Southern  Appalachian  Mountains  through- 
out the  greater  part  of  their  extent.  It  does  not  form  a  continu- 
ous divide,  as  the  Blue  Ridge,  but  is  cut  through  by  numerous 
streams.    From  the  Doe  River  northeastward  the  ranges  fronting 


CENTKAL   MOUNTAIN   GROUPS.  323 

upon  the  Appalachian  Vallej^  are  long  straight  ridges  with  few 
lateral  spurs ;  that  is,  they  closely  resemble  the  valley  ridges  al- 
ready described.  Although  they  are  to  be  regarded  as  members 
of  the  mountain  belt,  since  there  is  no  lowland  between  them  and 
the  Blue  Ridge,  they  differ  materially  from  the*  Unakas.  The 
latter  may  be  considered  as  terminating  between  the  Doe  and 
Nolichucky  rivers.  Thence  southwestward  the  range  is  fairly 
continuous  for  200  miles  to  northern  (Jeorgia,  although  its  dif- 
ferent portions  bear  many  local  names. 

As  already  stated,  the  highest  point  in  the  Blue  Ridge,  and 
the  one  reaching  an  altitude  approaching  f),0()()  feet,  is  Grand- 
father Mountain.  From  this  point,  in  whicli  the  Blue  Ridge  au<l 
the  Unakas  may  be  regarded  as  uniting,  an  irr(^gular  mountain 
range  extends  nearly  due  west  GO  miles  to  Paint  Rock  on  the 
French  Broad  River.  This  is  the  northern  division  of  the  Una- 
kas. East  of  the  Nolichucky  it  embraces  Haw,  Roan,  and  Unaka 
mountains;  and  between  the  Nolichucky  and  French  Broad,  th(? 
Bald,  Big  Butt,  and  Cow  Bell  niovintains.  Beyond  the  French 
Broad  the  range  has  greater  unity,  and  reaches  its  tyjiical  devel- 
opment in  the  Great  Smoky  Mountains,  which  form  a  massive 
chain,  continuous,  except  for  Big  Pigeon  Gorge,  for  75  mUes  to 
the  Little  Tennessee  River.  Beyond  this  the  range  is  made  up 
of  smaller  groups,  separated  by  frequent  river  gorges.  It  includes 
the  Sassafras,  Unaka,  Frog,  and  Cohutta  mountains,  terminating 
with  the  latter  group  in  northei'n  Georgia. 

Compared  with  the  Blue  Ridge,  the  Unaka  Range  reaches  a 
considerably  greater  average  altitude,  and  contains  most  of  the 
higher  peaks  in  the  Southern  Appalachians.  While  the  Blue 
Ridge  contains  only  4  points  above  5,000  feet  in  altitude,  the 
Unakas  have  18  or  more  above  5,000 ;  and  of  these,  8  are  above 
(5,000.  Not  only  have  they  gi-eater  altitude,  but  their  slopes  are 
steeper,  and  their  outlines  more  angular  and  rugged.  The  Blue 
Ridge  is  generally  steep  only  on  the  southeastern  side,  while  the 
Unakas  are  equally  steep  on  both  sides,  and  slopes  ^^^th  a  descent 
from  crest  to  stream  of  4,000  feet  are  not  uncommon.  Many 
liigh  spurs  leave  the  central  chain,  and  between  them  are  deep 
V-shaped  ravines. 

The  Central  Moirntain  Groups  and  Itdcrmontane  VaUcjiti. — 
From  any  commanding  point  along  the  Unaka  Range  there  may 
be  seen  stretching  to  the  east  and  south  a  great  sea  of  peaks, 
ridges,  and  domes.     There  is  no  dominating  range,  but  most  of 


J24  IHK  SOI  riii;i;\  Arr.vL.uiUANs. 

the  peaks  reai'h  nearly  tlic  same  altitude,  and  aiipcar  like  the 
waves  OH  a  elioppy  sea,  rauge  after  range  growing  less  aud  less 
ilistiiict,  until  their  outlines  are  barely  distinguishalile  from  tlie 
l)hu'  sky  at  the  horizon. 

These  are  the  niouutaiu  gi'oups  which  occupy  the  central  por- 
tion of  the  belt  or  basin  ]>etweeu  the  outer  ranges.  The  culti- 
vated valleys  are  generallj-  hidden  from  view,  and  except  for 
an  occasional  clearing  on  the  mountain  sides,  and  the  grassy 
"  balds  "  on  a  few  of  the  higher  domes,  the  whole  region  appears 
to  1)e  covered  with  a  forest  mantle.  Only  i-arely  does  a  ledge  of 
naked  rock  appear  through  the  vegetation  ;  so  that  the  slopes 
are  smoothed  aud  softened,  aud  the  landscape  lacks  the  rugged 
chai-acter  of  uuforested  mountain  regions.  The  atmospheric 
effects  also  tend  to  produce  the  same  result.  The  blue  haze 
which  is  almost  never  absent  from  this  I'egion,  aud  which  is  rec- 
ognized in  the  names  of  both  the  Blue  Kidge  and  the  Great 
Smoky  Mountains,  softens  the  details  of  objects  comparatively 
near  at  hand,  and  gives  the  effect  of  great  tlistance  to  peaks  but 
a  few  miles  away.  By  reason  of  this  atmospheric  effect  these 
mountains  of  only  moderate  altitude  often  afford  more  impres- 
,sive  views  than  heights  aud  distances  two  or  three  times  as  great 
in  the  clear  air  of  the  West. 

Some  of  these  interior  groups  are  njore  or  less  isolated,  but 
most  of  them  are  in  some  degree  connected  with  one  or  the 
other  of  the  ranges  which  rim  the  basin.  They  generally  have 
the  form  of  short  i-anges  from  5  to  20  miles  iu  length,  carrying  a 
number  of  peaks  a  few  hundred  feet  above  the  iuterveuing  gaps, 
and  sending  off"  long  spurs  which  may  themselves  have  peaks  as 
high  as  the  main  ranges.  There  is  no  uuiformitj'  iu  their  treiul, 
although  iu  most  cases  it  is  across  the  axis  of  the  mountain  belt 
rather  thau  parallel  A\ith  it.  A  very  large  number  of  the  interior 
summits  reach  altitudes  between  4,000  aud  5,000  feet,  aud  a  few 
are  over  6,000.  The  Black  Mountains,  a  few  miles  north  of  Ashe- 
ville,  contain  the  highest  peaks  in  the  Appalachian  Mountains. 
Mount  ]\Iitcliell,  with  an  altitude  of  (5,711  feet,  is  the  highest 
point  east  of  the  Mississippi,  being  425  feet  higher  than  Mount 
Washington. 

Between  these  groui:)s,  aud  forming  a  sort  of  platform  above 
which  they  arise,  are  many  broad  valleys,  commonest  toward  the 
lieads  of  the  streams,  aud  hence  iu  the  southeastern  side  of  the 
basin;  that  is,  along  the  northwestern  base  of  the  Blue  Ridge. 


IMEKMUNTANE    VAULEYS.  325 

Only  the  smaller  streams  are  still  flowiiij;'  at  the  level  of  these 
valleys.  Followed  downstream  toward  the  northwest,  the  broad 
valleys  are  found  to  be  more  and  more  deejtly  eut,  until  finally 
all  trace  of  tiiem  is  lost,  and  the  streams  are  found  in  deej)  nar- 
row gorges.  These  gorges  in  which  the  streams  in  their  lower 
courses  flow  are  being  cut  backward  into  the  valleys  at  their 
head  waters:  hence  the  broad  valleys  were  evidently  formed 
under  conditions  different  from  tliose  prevailing  at  the  present 
time.  They  must  have  lieen  formed  near  sea  level,  when  their 
streams  had  cut  down  to  l)ase-level,  and  were  widening  their 
channels  by  latei'al  corrasion.  The  presence  of  these  high  valleys 
is  the  best  possible  evi<Ience  that  the  altitude  of  the  region  in 
which  they  are  found  has  been  increastMl  by  elevation  in  com- 
))aratively  recent  times. 

The  characteristics  of  these  iutermontane  valleys  are  admi- 
rably displayed  in  the  vicinity  of  Asheville,  N.C.  Seen  from  an 
altitude  of  about  2,200  feet,  the  region  appears  as  a  broad  level 
plain,  stretching  in  all  directions  to  the  ])ase  of  the  smTounding 
mountains,  which  rise  from  it  with  abrupt  slopes.  The  same 
plain  with  slight  rise  extends  far  up  the  Swannanoa  and  French 
Broad  rivers,  and  up  the  smaller  streams  among  the  }nountain 
spurs.  At  Asheville  the  river  has  cut  a  channel  a  little  more 
than  200  feet  deep  within  this  plain,  and  this  channel  increases 
rapidly  in  depth  toward  the  northwest,  in  which  direction  tlie 
river  and  its  trilnitary  streams  have  deejjly  dissected  the  i)lain. 
Its  remnants,  however,  still  reach  a  common  level,  so  that  it  can 
be  easily  reconsti-ucted.  Eastward  on  the  Swannanoa,  and  south- 
ward on  the  French  Broad,  the  plain  is  less  and  less  dissected, 
and  toward  the  head  waters  of  these  streams  the  broad  valleys 
are  almost  perfectly  preserved.  These  iutermontane  valleys  ar(i 
found  on  all  the  northwestward-flowing  streams  of  the  mountain 
belt;  but  they  increase  in  extent,  and  at  the  same  time  dtM'rease 
in  altitude,  toward  the  southwest.  On  the  French  Broad  the 
altitude  of  the  valley  is  about  2,200  feet ;  on  the  Little  Tennessee, 
2,000;  on  the  ujiper  lliwassee,  1,800;  on  the  Ocoee,  1,700;  on  the 
Coosawattee,  1,500 ;  on  the  Etowah,  1,100 ;  and  on  the  Tallapoosa, 
1,000.  They  ai)pear  on  the  first  three  of  the  above-named 
streams  as  des<'ribed  on  the  French  Broad, — level  a ivnas,  walled 
in  upon  all  sides  by  the  encircling  mountains,  with  a  narrow 
gateway  leading  westward  through  the  Unakas  to  the  Gi'eat 
Valley.     Southward  from  the  Hiwassee,  the  adjacent  valleys 


326  THli   SOITHEKN    APPALACHIANS. 

merge  with  low  divides,  and  the  niouutain  groups  are  more 
completely  isolated.  Still  further  south,  on  the  Etowah  and 
Tallapoosa,  the  valleys  are  so  broadly  d<'veloped  that  the  divides 
separating  adjacent  basins  are  scarcely  pei'ceptible,  and  the  only 
mountains  remaining  are  isolated,  island-like  Monadnocks.  Ex- 
cellent examples  of  the  latter  are  seen  in  Kennesaw  and  Lost 
mountains,  in  northern  CJcorgia.  From  a  distance  of  a  few  miles 
they  appear  as  smooth  oval  domes,  rising  with  symmetrical 
slopes  above  a  level  plain.  This  plain  is  slightly  etched  by  the 
present  stream  channels,  which  are  from  50  to  150  feet  in  depth, 
but  on  the  horizon  it  makes  a  i)eifectly  even  sky  line.  It  ex- 
tends entirely  across  the  mountain  belt  from  the  Great  Vallej-  to 
the  Piedmont  Plain,  southwest  from  the  vicinity  of  Marietta  to 
the  Alabama  line,  iutei'vupted  only  by  a  few  low  Monadnocks. 
In  Alabama  it  is  less  perfectly  developed,  and  the  interrupted 
Appalachian  Mountains  reappear  in  the  Talladega  Eange.  The 
latter  forms  a  narrow  mountain  group  50  miles  in  length,  con- 
sisting of  a  high  central  ridge  bordered  by  low  hills.  It  should 
properly  be  considered  the  southern  member  of  the  Unakas,  al- 
though separated  from  the  main  range  by  an  interval  of  nearly 
100  miles. 

Dependence  of  Surface  Forms  on  the  Ch.\eacter  of  the 
KocKS  IN  THE  Mountain  Belt. — It  was  shown  in  a  preceding 
part  of  this  monograjih  that  the  physiography  of  the  Cumber- 
land Plateau  and  of  the  Great  Appalachian  Valley  Avas  most  in- 
timately connected  with  the  character  and  attitude  of  the  rocks 
underlying  those  regions.  It  was  there  shown  that  horizontal 
beds  of  varying  hardness  are  carved  by  streams  into  plateaus; 
and  that  the  same  beds,  when  tilted,  produce  long,  narrow 
ridges.  In  like  manner  the  form  of  the  surface  in  the  moun- 
tain belt  is  in  large  measure  dependent  on  the  character  of 
the  underlying  rocks,  although  its  greater  altitude  is  due  in  part 
to  recent  uplift. 

In  their  behavior  toward  the  agents  of  erosion,  the  rocks  of 
this  region  differ  from  those  toward  the  west  chiefly  in  being 
more  homogeneous.  They  consist  in  part  of  crystalline  rocks 
which  have  solidified  from  a  molten  state,  as  granite  and  diorite, 
with  crystalline  schists  derived  from  them;  and  in  part  of  slates 
and  conglomerates,  sedimentary  rocks,  which  have  been  more 
or  less  altered  by  heat  and  ])ressure.  Excepting  a  few  beds  of 
marble,  limestones  are  entirely  wanting.     The  original  differ- 


DRAINAGE.  327 

«nces  in  harduess  between  such  sedimentary  beds  as  shale 
and  conglomerate  have  been  nearly  obliterated  by  subsequent 
changes  which  tliey  have  uiidei-gone,  so  that  they  present  nearly 
the  same  degree  of  resistance  to  the  agents  of  erosion.  For 
this  reason  the  mountain  ranges  do  not  generally  conform  in 
trend  to  the  strike  of  the  rocks ;  while  there  is  a  very  uniform 
northeast  strike  within  the  mountain  belt,  the  crests  of  the 
interior  ranges  in  particular  are  extremely  irregular,  and  tlie 
long  spurs  are  quite  as  apt  to  cut  across  the  stioke  as  to  fol- 
low it. 

Some  differences  in  the  underlying  rocks,  however,  find  ex- 
pression in  slight  differences  in  the  topographic  forms.  Thus 
the  southeastern  portion  of  the  mountain  belt  is  occupied  almost 
exclusively  by  crystalline  rocks,  and  these  generally  give  rise 
to  broad  and  massive  domes  with  smooth  contours.  Such  forms 
characterize  the  Blue  Ridge  and  adjacent  mountain  groups.  The 
northwestern  portion  of  the  l:)elt,  on  the  other  hand,  is  occupied 
chiefly  by  metamorphic  rocks.  These  yield  less  i-eadily  to  dis- 
integration than  the  wholly  crystalline  rocks :  hence  the  gi'eater 
altitude  of  the  Unaka  Range,  and  the  prevalence  there  of  shai'p 
peaks  rather  than  of  rounded  domes. 


DRAINAGE  OF   THE   SOUTHERN   APPALACHIANS. 

The  streams  of  the  Southern  Appalachians  have  already  been 
frequently  mentioned  in  the  foregoing  physiographic  description 
of  the  region,  but  the  drainage  requires  a  few  words  of  further 
explanation. 

The  waters  falling  ujion  various  parts  of  the  region  find  their 
way  either  eastward  to  the  Atlantic,  southward  directly  to  the 
(xuK  of  Mexico,  or  to  the  Mississippi  and  thence  to  the  Gulf. 
The  divide  between  the  Atlantic  and  Grulf  drainage  follows  the 
crest  of  the  Blue  Ridge,  as  already  described,  from  the  Roanoke 
south  westward.  The  eastward-flowing  streams  are  pressing  this 
divide  gi-adually  westward  by  the  capture  of  territory  from  less 
favorably  situated  streams  west  of  the  divide.  Cases  of  recent 
capture  are  seen  at  the  head  of  the  Linden  and  Tallulah  rivers, 
the  falls  on  those  streams  showing  that  the  newly  acquired  ter- 
ritory has  not  yet  been  in  their  possession  sufficiently  long  to  be 
■completely  su1)dued.     Northwest  of  the  divide  the  streams  flow 


328  THE   SOUTHERN    APPALACHIANS. 

at  first  in  the  high  valleys,  many  of  which  were  evidently  formeil 
by  larger  streams  than  those  now  oerupying  them.  Leaving  the 
Blue  Ridge,  with  its  gentle  slopes  and  low  gaps,  thej'flow  north- 
westward in  deepening  channels,  directly  toward  the  higher  and 
more  rugged  Unakas,  which  they  cut  through  in  narrow  gorges. 
Emerging  upon  the  Appalachian  Valley,  those  south  of  Kew 
River  are  intercepted  by  triuik  streams,  and  led  oft"  toward  tiie 
southwest.  From  New  River  to  the  (leorgia  line  the  trunk 
stream  is  the  Tennessee,  which  leaves  its  southeastward  course 
and  at  the  same  time  the  broad  Apijalachiau  Valley  by  an  abriipt 
bend  at  Chattanooga,  traversing  the  Cumberland  Plateau  in  a 
narrow  gorge  evidently  much  younger  than  other  portions  of  its 
valley.  Southward  from  the  Georgia  line  the  tritnk  stream  is  the 
Coosa,  which  flows  directly  to  the  Gulf,  following  the  axis  of  the 
Great  Valley. 

The  divide  between  the  Tennessee  system  and  streams  flow- 
ing directly  to  the  Gulf  leaves  the  Blue  Ridge  in  northern 
Georgia,  and  follows  an  irregular  line  toward  the  west,  crossing 
successively  the  mountain  l)elt,  the  Great  Valley,  and  the  pla- 
teaus. It  is  peculiar  in  not  following  the  crest  of  a  ridge  for  any 
distance,  but  in  cutting  across  ridges  and  vallej's  marked  in 
many  places  by  a  barely  perceptible  rise  of  the  land.  There  is 
evidence  that  this  diA'ide,  like  the  gorge  of  the  Tennessee  through 
the  plateau,  is  extremely  young;  that  until  comparatively  recent 
times  all  the  waters  flowing  west  from  the  Blue  Ridge  found 
their  way  directly  to  the  Gulf  across  the  present  Tennessee-Coosa 
divide. 

The  stream  courses  within  the  valley  belt  show  a  close  ad- 
justment to  the  structure  of  the  region.  In  general  they  are 
located  upon  belts  of  soft  rocks;  and  when  they  leave  these, 
they  always  cross  intervening  hard  beds  by  the  most  direct 
course  at  I'ight  angles  to  the  strike.  They  more  often  occupy 
the  axes  of  anticlines  than  of  synclines,  so  that  they  nnist  have 
migrated  to  their  present  locations  by  the  process  of  stream 
adjustment  outlined  by  Mr.  Willis  in  Monograph  No.  6. 

PHYSIOGRAPHIC  DEVELOPMENT   OF   THE   SOUTHERN 
APPALACHIANS. 

Having  before  us  the  main  physiographic  features  of  the 
Southern  Appalachian  region,  we  are  prepared  to  follow  an  out- 


PHYSIOGRAPHIC   DEVELOPMENT.  :]L'i) 

Hue  of  the  history  of  its  development.  Its  earlier  history,  wliile 
the  region  was  in  part,  at  least,  covered  by  the  sea,  is  read  in  the 
sedimentary  rocks ;  while  the  later  chapters,  covering  the  i)eriods 
during  which  it  has  been  dry  land,  are  inscribed  in  the  tonus  of 
the  land  surface  and  the  relations  of  its  streams. 

Studying  the  rocks  of  the  three  western  divisions  of  the  jirov- 
iuce,  we  know  that  the  sediments  of  which  they  were  oomijosed 
were  derived  largely  from  laud  lying  toward  the  southeast,  prob- 
ably in  the  region  now  occupied  by  the  Piedmont  Plain  and 
beyond.  In  very  early  times  the  sea  may  have  covered  what  is 
now  the  Blue  Ridge;  but,  if  so,  the  shore  line  was  early  pushed 
toward  the  northwest,  uncovering  to  erosion  the  present  moun- 
tain l)elt,  which  furnished  much  of  the  material  foi-  the  later 
sedimentary  rocks.  For  a  long  tinu3  the  sea  margin  was  near 
the  northwestern  side  of  the  mountain  belt,  oscillating  within 
narrow  limits,  but  gradually  nngrating  westward.  Sometiiing 
can  be  learned,  from  the  sedimentai-y  rocks  thus  laid  down,  of 
the  old  land  area  from  which  their  nuiterials  were  derived. 
Thus  conglomerates  indicate  steep  slopes  and  I'apid  streams, 
while  limestones  point  to  the  opposite  extreme, — a  land  with 
low  relief  and  sluggish  streams,  able  to  supply  but  litth*  irag- 
meutal  material  to  the  adjoining  sea.  At  least  two  great  cycles 
of  erosion  are  thus  recorded  in  which  the  surface  of  the  old  con- 
tinent was  worn  down  from  a  consideralde  altitude  nearly  to 
base-level. 

Shortly  after  the  close  of  the  Carboniferous  period  thcf  entire 
Southern  Appalachian  Province  was  finally  lifted  above  sea 
level,  and  its  subsequent  history  is  recorded  chielly  in  laiul 
forms.  At  the  same  time  that  the  region  was  elevated,  the  strata 
in  a  long  narrow  belt  adjacent  to  the  old  shore  line  w(>re  in- 
tensely folded.  The  streams  flowing  from  the  old  land  into  the 
interior  sea  before  the  emergence  doubtless  continued  in  the 
same  direction,  extending  their  lowei'  courses  across  the  newly 
added  laud  as  successive  belts  emerged.  Since  the  process  of 
folding  was  exceedingly  slow,  they  may  have  held  their  original 
courses  for  a  long  time  in  spite  of  the  folds  rising  across  tiieir 
path.  These  folds,  however,  although  not  directly  able  to  turn 
the  rivers  aside,  l)i-oiight  bands  of  soft  rocks  above  base-level, 
aiid  so  were  able  indirectly  to  accomplish  that  result.  Streams 
flowing  southward  parallel  with  the  folds  were  located  entirely 
upon  soft  rocks,  and  so  were  able  to  deepen  their  channels  luoi-e 


:;oU  IHK    SUirUEKN    APPAIACUUNS. 

rai>itlly  tliau  those  tlovviug  westward  across  iiiauy  hard  beds: 
liciK-e  the  streams  iiarallel  with  the  folds  encroached  iipou  the 
territory  of  tlie  transverse  streams,  aud  successively  captured 
them,  and  led  them  by  southwestward  com'ses  directly  to  the 
(lulf.  When  once  fairly  started,  the  couqiiest  proceeded  rapidly 
toward  the  northeast;  but,  before  it  had  reached  NewEiver,  the 
latter  had  been  able  to  sink  its  own  channel  so  deei)ly  that 
the  Holston  could  not  cut  through  its  banks  and  divert  it.  It 
intrenched  itself  successfidly  against  the  encroachments  of  its 
marauding  neighbor.  New  River  therefore  continues  north- 
westward from  its  sovu'ce  on  the  Blue  Ridge,  across  the  moun- 
tain belt,  the  Great  Valley,  and  the  Cumberland  Plateau.  It 
is  the  only  stream  in  the  entire  Ai)palachian  Pro^dnce  which 
retains  throughout  its  eutii"e  length  approximately  its  original 
position. 

Following  this  uplift  was  a  long  period  during  which  the 
region  was  subjected  to  the  physiographic  processes  constituting 
gradation.  These  have  been  described  in  preceding  monographs. 
Probably  base-leveling  was  several  times  carried  nearly  to  com- 
pletion during  this  jteriod;  but  the  peneplains  thus  formed 
were  destroyed  by  subsequent  erosion,  and  no  record  of  them 
i-emains.  Finally,  toward  the  close  of  Cretaceous  time,  the 
whole  province  was  reduced  to  a  nearly  featureless  plain,  re- 
lieved only  by  a  few  groups  of  jNIonadnocks  whei'e  the  highest 
Tiioiintains  now  stand. 

After  the  process  of  base-leveling  was  nearly  completed  — 
that  is,  toward  the  close  of  the  Cretaceous  —  the  region  was 
again  lifted,  but  unequally,  so  that  at  the  same  time  its  sm-face 
was  warped.  The  streams  had  become  sluggish,  but  the  effect 
of  the  uplift  was  to  stimidate  them  to  renewed  acti\'ity.  They 
began  at  once  to  lower  their  channels  in  the  old  peneplain,  and, 
when  thej^  had  reached  the  new  base-level,  to  form  a  new  pene- 
plain by  lateral  corrasion.  This  process  went  on  most  ra^iidly 
on  areas  underlain  by  easily  erodible  rocks;  so  that  the  ne^v 
{)eneplain  was  extensively  developed  on  the  limestones  of  the 
valley  l)elt,  while  the  streams  still  flowed  approximately  at  the 
old  level  on  tlie  hard  sandstones  of  the  plateau  and  the  slates  of 
the  mountain  belt.  It  is  from  these  remnants  preserved  upon 
areas  of  hard  rocks  that  we  are  able  to  reconstruct  the  older 
peneplain.  The  largest  remnants  are  seen  in  the  smooth,  even 
summits  of  the  Cumberland  Plateau.    It  is  also  preserved  in  the 


KELATION   OF   UECENT   UPLIFT   AND   PRESENT   ALTITUDE.        331 

even  crests  of  the  valley  ridges,  ;iii<l  tlu;  high  valleys  witliiu  the 
mouutiiin  belt. 

The  formation  of  the  second  peneplain  was  well  advanced 
over  areas  of  soft  rocks,  when  the  region  was  again  sul>jected  to 
a  series  of  verti(!al  oscillations,  th<^  final  result  of  which  was  ele- 
vation accompanied  by  warping.  As  before,  the  effect  of  the 
elevation  was  to  stimulate  the  streams  so  that  they  began  cutting 
upon  the  last-formed  penei)lain, — a  process  in  which  they  are 
still  engaged. 

During  the  last  series  of  oscillations  mentioned  above,  some 
important  changes  were  produced  in  the  drainage.  Previous  to 
this  the  waters  of  the  valley  belt  from  New  Kiver  southwestward 
had  collected  into  a  single  trunk  stream,  which  flowed  aci'oss  the 
present  divide  directly  to  tlie  (lulf  liy  tlu*  ]tresent  course  of  the 
Coosa  River.  A  peculiar  set  of  conditions  for  a  time  gave  suffi- 
cient advantage  to  a  westward-flowing  stream  to  enable  it  to  cut 
through  the  jjlateau,  and  divert  the  trunk  stream  westward  to  the 
present  coiirse  of  the  Tennessee. 

RELATION    OF   KKCENT    UPLIFT   AND   PRESENT   ALTITUDE. 

It  was  shown  in  describing  the  Appalachian  Mountains  that 
from  the  culminating  point  in  North  Carolina  the  average  al- 
titude of  the  belt  decreases  southwestward;  that  the  bounding 
ranges,  the  Blue  Ridge  and  Uuakas,  as  well  as  the  interior  moun- 
tain groups,  become  less  massive  and  more  deeply  cut  by  trans- 
verse (h'ainage  chainiels ;  and  that  the  intermoutaue  valleys, 
which  in  the  northern  part  of  the  belt  ai-e  walled  in  by  moun- 
tains upon  all  sides,  occupy  an  increasing  proportion  of  the  area, 
until  in  Georgia  they  form  a  level  plateau  stretching  entirely 
across  the  belt,  and  intei-rupted  only  by  a  few  isolated  IMonad- 
nocks.  The  cause  of  this  gradual  decrease  in  altitude  toward 
the  southwest  can  now  be  understood.  It  is  not  due  to  tlie  ]ii-(»s- 
enee  of  more  easily  erodible  rocks  in  the  southern  than  in  the 
northern  portion  of  the  belt;  for  they  are  essentially  the  same 
kinds,  and,  in  their  unweathered  condition,  offer  tho  sam<'  degree 
of  resistance  to  agents  of  gradation.  The  cause  is  rather  in  the 
different  amounts  of  uplift  which  the  two  regions  have  suffered 
in  recent  geologic  periods.  It  was  stated  above  that  the  Soutli- 
ern  Appalachinns  had  been  several  times  more  or  less  comjiletely 
base-leveled,  and  that  each  base-leveling  period  was  followed  l)y 


33-2  THE    SOl'THEKN"    ArrAl.ACIllANS. 

an  uplift  -which  stimuhited  the  streams  to  renewed  activity  upon 
the  peneplain.  It  is  evident  that  the  depth  of  tlie  gorges  cut  by 
the  rejuvenated  streams  would  depend  on  tlie  amount  of  the  up- 
lift ;  and  hence  the  height  of  the  mountains,  which  are  simply 
remnants  of  the  deeply  dissected  peneplain,  would  also  dej^end 
on  the  amomit  of  u^dift.  In  regions  whore  tlie  uplift  was 
great,  the  intervening  portions  of  the  peneplain  would  long 
remain  as  high  mountain  masses ;  and,  on  the  other  hand,  where 
the  uplift  was  slight,  the  streams  would  quickly  cut  down  to  the 
new  base-level,  and  begin  the  task  of  removing  the  interven- 
ing highlands:  hence  moderate  iiplift  would  not  only  give  rise 
to  low  mountains,  but  would  favor  the  formation  of  isolated 
Mouadnocks. 

Again,  during  the  later  stages  of  the  base-leveling  process,  the 
rocks  of  a  region  became  deeply  weathered;  so  that,  when  the 
streams  are  accelerated  by  uplift,  erosion  is  at  first  much  more 
rapid  in  the  soft  surface  rock  than  it  is  when  the  fresh  rock  be- 
neath is  reached :  hence,  if  the  i;plift  in  any  region  is  but  one  or 
two  hundred  feet,  the  streams  may  encounter  only  soft  material 
in  forming  the  new  peneplain ;  whereas,  if  the  uplift  is  one  or 
two  thousand  feet,  far  the  greater  part  of  their  work  will  be  in 
hard,  unweathered  material.  Now,  it  was  shown  that  in  the 
Southern  Appalachians  two  peneplains  are  sulheieutly  well  pre- 
served so  that  we  are  able  to  reconstruct  their  surfaces,  and 
determine  the  amount  of  uplift  which  they  have  subsequently 
undergone.  In  both  of  these  cases  the  uplift  terminating  one 
base-leveling  cycle  and  inaugurating  another  has  been  unequal, 
greatest  near  the  cidmiuating  point  of  the  Appalachians,  and 
gradually  decreasing  southwestward.  Moreovei",  it  seems  proba- 
ble that  the  elevation  of  previous  i)eneplains  in  the  same  region 
has  been  of  the  same  character,  greatest  toward  the  north,  and 
decreasing  soiithwestward :  hence  the  present  decrease  in  altitude 
of  the  Southern  Appalachian  Mountains  toward  the  southwest, 
and  the  corresponding  increase  in  the  proportion  of  area  occupied 
by  base-leveled  valleys,  are  traced  directly  to  differential  uplift 
in  recent  geologic  periods. 

INFLUENCE  OF   PHYSIOGRAPHY   ON   SOCXAX,   AND   INDUSTRIAL 
DEVELOPMENT. 

The  physiography  of  any  region  determines  to  a  large  extent 
the  character  of  the  social  and  industrial  development  of  its 


INl'U'ENCE   ON    .SOCI.VL   UEVELurMENT.  oo3 

people.  It  als(j  lias  an  iiiflueiico  .soinewhat  Ifss  diret't  oti  their 
moral  and  intellectual  develupnieut.  Some  of  the  more  obvious 
ways  in  which  the  physiography  of  the  Southern  Appalachians 
has  aifected  the  ijeoplc  and  institutions  will  be  pointed  out. 

The  first  settlenjent  of  the  region  was  along  th(>  Atlantic 
(joast  and  up  the  navigable  rivers  to  the  "fall  line."  Here  the 
streams  leave  their  rocky  channels  on  the  Piedmont,  by  a  series 
of  rapids  and  falls,  for  deep  cliannels  across  the  Coastal  Plain. 
At  the  head  of  navigation  on  the  rivei's,  trading  posts  wei'e  at 
first  established,  which  have  since  developed  into  thriving  cities. 
From  these  outposts  pioneers  pushed  farther  inlaml  ov'er  the 
whole  Piedmont  Plain,  and  up  to  the  heads  of  tlie  fei'tile  valleys 
among  the  eastern  spurs  of  the  Appalachian  Mountains.  For  a 
time  the  Blue  Ridge  checked  furtlier  advance  westward  ;  but  this 
was  soon  crossed,  and  the  interniontane  valleys  upon  its  western 
side  occupied.  Beyond  these  were  the  ragged  Unakas,  which 
long  presented  an  insurmountable  obstacle  to  further  progre.ss. 
To  th(^  natural  difficulties  of  ti'avel  were  added  the  dangers 
from  the  warlike  (Jhei'okee  Indians,  who  found  the  thirk,  narrow 
ravines  well  suited  for  their  mode  of  waii'are. 

Hunters  brought  back  to  the  eastei-n  settlements  alluring 
tales  of  rich  valley  lands  beyond  the  mountains,  and  even  before 
the  Revolution  a  few  hardy  pioneers  had  settled  iu  the  Appala- 
chian Valley.  Unable  to  pass  the  Unaka  Range,  two  possible 
routes  to  the  region  W(n"e  left, — one  by  way  of  the  James  or 
Roanoke  gaps,  through  the  Bhu'  Ridge,  and  thence  southwest- 
ward  down  the  valley ;  and  the  other  through  northern  Georgia, 
around  tlie  soutlnM-n  end  of  tTie  mountain  ranges.  The  latter 
I'oiite  was  little  used  on  account  of  the  hostile  Creeks  and  (,'hero- 
kees,  and  nearly  the  entire  immigration  of  the  western  portion  of 
the  Appalachians  came  in  by  the  northern  route.  In  the  early 
decades  of  the  century  the  region  was  I'apidly  settled,  chiefly 
from  the  Carolinas,  Virginia,  and  (xeorgia.  The  Cherokees  were 
gi'adually  crowded  within  narrower  limits  as  their  rich  lands 
were  first  coveted  and  then  ajiprojiriated  by  the  whites.  Finally, 
between  1830  and  lS4(t,  theii-  liunting  grounds  were  i)urchased 
by  the  Fedei'al  Government,  and  most  of  the  tribe  was  re- 
moved to  the  Indian  Territory.  A  few  families  of  the  tiibe 
refused  to  leave  their  old  home,  and  coidd  not  be  dislodged 
from  the  remote  mountain  valleys  to  which  they  had  retreated. 
Their  descendants   still   occupy  a    small   reservation  in  west- 


334  THE   SOUTHERN    APPALACHIANS. 

evil  North  Carolina,  only  jiartially  oivilizcd  l>y  coutact  with  their 
neighbors. 

The  Appalachian  Mountains,  and  in  some  measure  also  the 
Cumberland  Plateaus,  thus  acted  as  barriers  to  the  advance  of 
settlement ;  so  that  the  tide  of  immigration  was  for  a  time 
cheeked,  and  turned  from  the  more  direct  course  to  one  which 
oifered  less  resistance.  With  the  advent  of  railroads  the  same 
lines  of  least  resistance  were  followed  which  had  directed  tlie  tide 
of  immigration.  The  products  of  the  interior  sought  an  outlet 
to  the  east ;  but  from  the  Koanoke  southward  for  350  miles  the 
Appalachian  Mountains  offered  a  serious  obstacle,  and  not  until 
after  1880  was  this  portion  of  the  mountain  belt  crossed  by  any 
raih'oad.  Past  the  southern  end  of  the  mountains,  through  north- 
ern Georgia,  there  was  a  natural  outlet  for  the  interior  across 
the  base-leveled  plain  already  described ;  and  this  was  utilized 
for  one  of  the  earliest  roads  built  in  the  South. 

Few  obstacles  were  met  in  building  roads  on  the  Piedmont 
Plain,  and  comparatively  few  in  the  Ap})alachian  Valley.  AVhere 
these  natural  routes  are  intersected  by  the  transverse  route 
across  the  mountain  belt,  there  thriving  cities  have  grown  up. 
Atlanta,  the  "  date  City,"  stands  at  the  portal  of  the  Southern 
Appalachians,  on  the  only  natural  route  from  the  Tennessee 
basin  to  the  southeast. 

For  a  long  distance  on  either  side  of  Chattanooga,  both  to- 
ward the  north  and  south,  the  Cumberland  Plateaus  present  high, 
steep  escarpinents  toward  the  valley,  offering  serious,  if  not  in- 
superable, obstacles  to  east  and  west  roads.  Toward  the  west, 
however,  the  plateaus  are  deepfy  cut  by  transverse  streams, 
along  which  roads  have  been  built  with  <-omparative  ease.  Thus 
Chattanooga  is  also  a  "  gate  city,"  standing  at  the  portal  through 
which  must  pass  all  traffic  between  the  great  Interior  Lowlands 
and  the  Southern  Appalachian  Valley. 

Ease  of  communication  is  so  important  a  factor  in  modern 
social  development,  that  regions  abundantly  supplied  "with  I'ail- 
roads  advance  far  beyond  those  still  dependent  t)u  less  I'apid 
transit :  hence  there  are  greater  differences  between  the  social 
conditions  in  the  valleys  and  among  the  mountains  than  could 
possibly  exist  when  th(>  two  regions  were  more  nearly  on  an 
equality  in  this  respect.  The  peojde  remote  from  railroads  are 
relatively  much  more  isolated  than  they  were  when  the  only 
means  of  travel  between  the  different  parts  of  the  country  were 


INFLUENCE   ON    SUCl.YL   DEVELOPMENT.  335 

on  horseback  or  by  stage.  Many  of  the  people  in  this  region 
have  been  scarcely  at  all  affected  by  the  modern  industrial  and 
social  revolutions  which  have  been  going  on  around  them.  In 
some  of  tlie  more  remote  mountain  valleys  the  mode  of  life  doi's 
not  diffei'  essentially  from  that  which  jtrevailed  throughout  most 
of  the  country  during  colonial  times.  Practically  everything 
consumed  in  the  household  is  of'domcstic  manufacture,  and  tlit- 
people  have  few  wants  which  must  be  supplied  from  the  out- 
side world.  In  these  isolated  communities  are  found  the  direct 
descendants  of  early  Virginia  and  Carolina  immigrants,  Avitii 
scarcely  a  trace  of  foreign  admixture.  They  are  perhaps  tin- 
purest  stock  in  the  United  Statesi.  Curious  archaic  customs  and 
forms  of  speech  are  preserved  among  them  which  have  entirely 
disappeared  elsewhere. 

There  is  still  another  way  in  which  physiography  has  affected 
the  people,  scarcely  less  important  than  by  controlling  the  ease  of 
intercommunication  between  communities.  Until  within  a  few 
years  the  people  of  the  Southern  Appalachian  region  have  been 
engaged  almost  exclusively  in  agricultural  pursuits.  Differences 
in  soil  and  climate  have  determined  the  crops  which  could  be 
raised  with  profit,  and  hence  mode  of  cultivation  and  social  con- 
ditions. Only  the  lowlands  on  either  side  of  the  Appalachians 
and  the  southern  portion  of  the  Great  Valley  were  suited  to  the 
cultivation  of  cotton:  hence  in  the  highlands,  where  diversified 
crops  and  small  farms  were  the  rule,  the  institution  of  slavery 
did  not  gain  a  firm  footing,  as  it  did  in  the  cotton-raising 
districts.  Some  counties  of  North  Carolina  even  now  do 
not  contain  a  single  negro.  These  tlitt'erent  social  conditions 
which  prevailed  for  two  generations  prior  to  the  Civil  War, 
and  which  were  traceable  dii'ectly  to  i)hysiographic  causes, 
have  left  effects  upon  the  people  which  will  i-e(|nii'e  many  years 
to  eradicate. 

The  industi'ial  revolution  now  in  progress  in  the  South,  by 
which  it  is  being  converted  from  a  i)ur<^ly  agricultural  to  a  manu- 
facturing region,  is  due  in  large  part  to  physiographic  causes. 
Within  a  belt  embracing  the  eastern  portion  of  the  plateau  and 
the  western  edge  of  the  valley,  conditions  are  extremely  favor- 
able for  the  cheap  production  of  iron.  Fuel  from  the  plateaus, 
and  ore  and  flux  from  the  valley,  are  brought  together  Avitli  a 
minimum  of  expense;  and  manufacturing  towns  are  springing 
up  within  this  l)elt  from  Virginia  to  central  Alabama. 


:i'iHi  THE   SOUTHERN    APPAL-iCHIANS. 

Cheap  j)ower  is  even  more  important  tliau  abundant  raw  mate- 
lials  in  bixikliiig  up  manufactures ;  and,  with  modern  improved 
methods  for  the  trausmissit)n  of  power  by  electricity,  water  is  to 
some  extent  rephicing  steam.  The  Southern  A])pakichians  are 
rich  in  water  power.  The  streams  whicli  flow  westward  from 
the  mountain  belt  hjiv(»  large  catchment  basins  in  the  high  inter- 
montane  valleys.  In  tlieir  courses  to  the  A]ipalachian  Valley  are 
many  rapids,  particularly  where  they  l)reak  through  the  Unaka 
Range;  and  much  of  the  power  now  going  to  waste  in  these 
rapids  will  undoubtedly  be  utilized  before  many  decades.  The 
manufacturing  communities  resulting  from  this  utiUzation 
will  be  directly  due  to  recent  uplift  of  the  Appalachian  Moun- 
tain belt. 

It  is  thus  seen  that  the  i)hysiography  of  the  Southern  Appa- 
lachians determined  lines  of  early  settlement,  and  directed  the 
subsequent  tide  of  immigration  l)y  which  the  region  was  peo- 
{>led;  that  it  determined  the  lines  of  traffic  and  travel,  the 
location  of  cities,  and  the  relative  development  of  different 
communities;  that  it  determined  the  occupations  and  there- 
1  )y  the  social  conditions  in  different  portions  of  the  region  ;  and, 
finally,  that  it  must  in  future  exercise  an  important  influence 
upon  its  industrial  development  and  the  material  welfare  of 
its  people. 


] 


I 


■^:k 


.!-■■. 


,.V«ac 


